diff --git a/marker/v2/builders/document.py b/marker/v2/builders/document.py
index a89b013a..af5d9f44 100644
--- a/marker/v2/builders/document.py
+++ b/marker/v2/builders/document.py
@@ -3,8 +3,10 @@
 from marker.v2.builders.layout import LayoutBuilder
 from marker.v2.builders.ocr import OcrBuilder
 from marker.v2.providers.pdf import PdfProvider
+from marker.v2.schema import BlockTypes
 from marker.v2.schema.document import Document
 from marker.v2.schema.groups.page import PageGroup
+from marker.v2.schema.registry import get_block_class
 
 
 class DocumentBuilder(BaseBuilder):
@@ -15,13 +17,14 @@ def __call__(self, provider: PdfProvider, layout_builder: LayoutBuilder, ocr_bui
         return document
 
     def build_document(self, provider: PdfProvider):
+        PageGroupClass: PageGroup = get_block_class(BlockTypes.Page)
         initial_pages = [
-            PageGroup(
+            PageGroupClass(
                 page_id=i,
                 lowres_image=provider.get_image(i, settings.IMAGE_DPI),
                 highres_image=provider.get_image(i, settings.HIGHRES_IMAGE_DPI),
                 polygon=provider.get_page_bbox(i)
             ) for i in provider.page_range
         ]
-
-        return Document(filepath=provider.filepath, pages=initial_pages)
+        DocumentClass: Document = get_block_class(BlockTypes.Document)
+        return DocumentClass(filepath=provider.filepath, pages=initial_pages)
diff --git a/marker/v2/builders/layout.py b/marker/v2/builders/layout.py
index 4683e890..0b4df842 100644
--- a/marker/v2/builders/layout.py
+++ b/marker/v2/builders/layout.py
@@ -7,10 +7,10 @@
 from marker.v2.builders import BaseBuilder
 from marker.v2.providers.pdf import PageLines, PageSpans, PdfProvider
 from marker.v2.schema import BlockTypes
-from marker.v2.schema.blocks import LAYOUT_BLOCK_REGISTRY
 from marker.v2.schema.document import Document
 from marker.v2.schema.groups.page import PageGroup
 from marker.v2.schema.polygon import PolygonBox
+from marker.v2.schema.registry import get_block_class
 from marker.v2.schema.text.line import Line
 
 
@@ -49,7 +49,7 @@ def add_blocks_to_pages(self, pages: List[PageGroup], layout_results: List[Layou
             layout_page_size = PolygonBox.from_bbox(layout_result.image_bbox).size
             provider_page_size = page.polygon.size
             for bbox in sorted(layout_result.bboxes, key=lambda x: x.position):
-                block_cls = LAYOUT_BLOCK_REGISTRY[BlockTypes[bbox.label]]
+                block_cls = get_block_class(BlockTypes[bbox.label])
                 layout_block = page.add_block(block_cls, PolygonBox(polygon=bbox.polygon))
                 layout_block.polygon = layout_block.polygon.rescale(layout_page_size, provider_page_size)
                 page.add_structure(layout_block)
diff --git a/marker/v2/builders/ocr.py b/marker/v2/builders/ocr.py
index bcf757a4..9f40da9a 100644
--- a/marker/v2/builders/ocr.py
+++ b/marker/v2/builders/ocr.py
@@ -6,9 +6,9 @@
 from marker.v2.builders import BaseBuilder
 from marker.v2.providers.pdf import PdfProvider
 from marker.v2.schema import BlockTypes
-from marker.v2.schema.blocks import Block
 from marker.v2.schema.document import Document
 from marker.v2.schema.polygon import PolygonBox
+from marker.v2.schema.registry import get_block_class
 from marker.v2.schema.text.line import Line
 from marker.v2.schema.text.span import Span
 
@@ -63,6 +63,9 @@ def ocr_extraction(self, document: Document, provider: PdfProvider) -> Tuple[Pag
         page_lines = {}
         page_spans = {}
 
+        SpanClass: Span = get_block_class(BlockTypes.Span)
+        LineClass: Line = get_block_class(BlockTypes.Line)
+
         for page_id, recognition_result in zip((page.page_id for page in page_list), recognition_results):
             page_spans.setdefault(page_id, {})
             page_lines.setdefault(page_id, [])
@@ -74,13 +77,13 @@ def ocr_extraction(self, document: Document, provider: PdfProvider) -> Tuple[Pag
                 image_polygon = PolygonBox.from_bbox(recognition_result.image_bbox)
                 polygon = PolygonBox.from_bbox(ocr_line.bbox).rescale(image_polygon.size, page_size)
 
-                page_lines[page_id].append(Line(
+                page_lines[page_id].append(LineClass(
                     polygon=polygon,
                     page_id=page_id,
                 ))
 
                 line_spans.setdefault(ocr_line_idx, [])
-                line_spans[ocr_line_idx].append(Span(
+                line_spans[ocr_line_idx].append(SpanClass(
                     text=ocr_line.text,
                     formats=['plain'],
                     page_id=page_id,
diff --git a/marker/v2/builders/structure.py b/marker/v2/builders/structure.py
index 90f950ce..b316ddb4 100644
--- a/marker/v2/builders/structure.py
+++ b/marker/v2/builders/structure.py
@@ -1,12 +1,9 @@
-from typing import Optional
-
-from pydantic import BaseModel
-
 from marker.v2.builders import BaseBuilder
 from marker.v2.schema import BlockTypes
 from marker.v2.schema.document import Document
-from marker.v2.schema.groups import GROUP_BLOCK_REGISTRY, ListGroup
+from marker.v2.schema.groups import ListGroup
 from marker.v2.schema.groups.page import PageGroup
+from marker.v2.schema.registry import get_block_class
 
 
 class StructureBuilder(BaseBuilder):
@@ -53,7 +50,7 @@ def group_caption_blocks(self, page: PageGroup):
 
             if len(block_structure) > 1:
                 # Create a merged block
-                new_block_cls = GROUP_BLOCK_REGISTRY[BlockTypes[block.block_type.name + "Group"]]
+                new_block_cls = get_block_class(BlockTypes[block.block_type.name + "Group"])
                 new_polygon = block.polygon.merge(selected_polygons)
                 group_block = page.add_block(new_block_cls, new_polygon)
                 group_block.structure = block_structure
diff --git a/marker/v2/converters/pdf.py b/marker/v2/converters/pdf.py
index 47135819..55caad9e 100644
--- a/marker/v2/converters/pdf.py
+++ b/marker/v2/converters/pdf.py
@@ -1,10 +1,11 @@
+from marker.v2.providers.pdf import PdfProvider
 import os
 
 os.environ["TOKENIZERS_PARALLELISM"] = "false" # disables a tokenizers warning
 
-from marker.v2.processors.sectionheader import SectionHeaderProcessor
-from marker.v2.providers.pdf import PdfProvider
 import tempfile
+from collections import defaultdict
+from typing import Dict, Type
 
 import click
 import datasets
@@ -14,17 +15,26 @@
 from marker.v2.builders.ocr import OcrBuilder
 from marker.v2.builders.structure import StructureBuilder
 from marker.v2.converters import BaseConverter
+from marker.v2.models import setup_detection_model, setup_layout_model, \
+    setup_recognition_model, setup_table_rec_model, setup_texify_model
 from marker.v2.processors.equation import EquationProcessor
+from marker.v2.processors.sectionheader import SectionHeaderProcessor
 from marker.v2.processors.table import TableProcessor
-from marker.v2.models import setup_layout_model, setup_texify_model, setup_recognition_model, setup_table_rec_model, \
-    setup_detection_model
 from marker.v2.renderers.markdown import MarkdownRenderer
+from marker.v2.schema import BlockTypes
+from marker.v2.schema.blocks import Block
+from marker.v2.schema.registry import register_block_class
 from marker.v2.processors.debug import DebugProcessor
 
 
 class PdfConverter(BaseConverter):
+    override_map: Dict[BlockTypes, Type[Block]] = defaultdict()
+
     def __init__(self, config=None):
         super().__init__(config)
+        
+        for block_type, override_block_type in self.override_map.items():
+            register_block_class(block_type, override_block_type)
 
         self.layout_model = setup_layout_model()
         self.texify_model = setup_texify_model()
diff --git a/marker/v2/providers/pdf.py b/marker/v2/providers/pdf.py
index d4492ef1..77d49c2f 100644
--- a/marker/v2/providers/pdf.py
+++ b/marker/v2/providers/pdf.py
@@ -4,11 +4,12 @@
 import pypdfium2 as pdfium
 from pdftext.extraction import dictionary_output
 from PIL import Image
-from pydantic import BaseModel
 
 from marker.ocr.heuristics import detect_bad_ocr
 from marker.v2.providers import BaseProvider
 from marker.v2.schema.polygon import PolygonBox
+from marker.v2.schema import BlockTypes
+from marker.v2.schema.registry import get_block_class
 from marker.v2.schema.text.line import Line
 from marker.v2.schema.text.span import Span
 
@@ -23,7 +24,7 @@ class PdfProvider(BaseProvider):
     flatten_pdf: bool = True
     force_ocr: bool = False
 
-    def __init__(self, filepath: str, config = None):
+    def __init__(self, filepath: str, config=None):
         super().__init__(filepath, config)
 
         self.doc: pdfium.PdfDocument = pdfium.PdfDocument(self.filepath)
@@ -105,6 +106,8 @@ def pdftext_extraction(self) -> Tuple[PageLines, PageSpans]:
             workers=self.pdftext_workers,
             flatten_pdf=self.flatten_pdf
         )
+        SpanClass: Span = get_block_class(BlockTypes.Span)
+        LineClass: Span = get_block_class(BlockTypes.Line)
         for page in page_char_blocks:
             page_id = page["page"]
             lines: List[Line] = []
@@ -120,7 +123,7 @@ def pdftext_extraction(self) -> Tuple[PageLines, PageSpans]:
                         font_weight = span["font"]["weight"] or 0
                         font_size = span["font"]["size"] or 0
                         spans.append(
-                            Span(
+                            SpanClass(
                                 polygon=PolygonBox.from_bbox(span["bbox"]),
                                 text=span["text"],
                                 font=font_name,
@@ -133,7 +136,7 @@ def pdftext_extraction(self) -> Tuple[PageLines, PageSpans]:
                                 text_extraction_method="pdftext"
                             )
                         )
-                    lines.append(Line(polygon=PolygonBox.from_bbox(line["bbox"]), page_id=page_id))
+                    lines.append(LineClass(polygon=PolygonBox.from_bbox(line["bbox"]), page_id=page_id))
                     line_spans[len(lines) - 1] = spans
             if self.check_line_spans(line_spans):
                 page_lines[page_id] = lines
diff --git a/marker/v2/schema/blocks/__init__.py b/marker/v2/schema/blocks/__init__.py
index d10f8759..09db403c 100644
--- a/marker/v2/schema/blocks/__init__.py
+++ b/marker/v2/schema/blocks/__init__.py
@@ -17,11 +17,3 @@
 from marker.v2.schema.blocks.table import Table
 from marker.v2.schema.blocks.text import Text
 from marker.v2.schema.blocks.toc import TableOfContents
-
-LAYOUT_BLOCK_REGISTRY = {
-    v.model_fields['block_type'].default: v for k, v in locals().items()
-    if isinstance(v, type)
-    and issubclass(v, Block)
-    and v != Block  # Exclude the base Block class
-    and not v.model_fields['block_type'].default.name.endswith("Group")
-}
diff --git a/marker/v2/schema/groups/__init__.py b/marker/v2/schema/groups/__init__.py
index a676ede2..43bf9829 100644
--- a/marker/v2/schema/groups/__init__.py
+++ b/marker/v2/schema/groups/__init__.py
@@ -4,11 +4,3 @@
 from marker.v2.schema.groups.list import ListGroup
 from marker.v2.schema.groups.picture import PictureGroup
 from marker.v2.schema.groups.page import PageGroup
-
-GROUP_BLOCK_REGISTRY = {
-    v.model_fields['block_type'].default: v for k, v in locals().items()
-    if isinstance(v, type)
-    and issubclass(v, Block)
-    and v != Block  # Exclude the base Block class
-    and (v.model_fields['block_type'].default.name.endswith("Group") or v.model_fields['block_type'].default.name == "Page")
-}
diff --git a/marker/v2/schema/registry.py b/marker/v2/schema/registry.py
new file mode 100644
index 00000000..bf17f99c
--- /dev/null
+++ b/marker/v2/schema/registry.py
@@ -0,0 +1,55 @@
+from typing import Dict, Type
+from importlib import import_module
+
+from marker.v2.schema import BlockTypes
+from marker.v2.schema.blocks import Block, Caption, Code, Equation, Figure, \
+    Footnote, Form, Handwriting, InlineMath, \
+    ListItem, PageFooter, PageHeader, Picture, \
+    SectionHeader, Table, TableOfContents, \
+    Text
+from marker.v2.schema.document import Document
+from marker.v2.schema.groups import FigureGroup, ListGroup, PageGroup, \
+    PictureGroup, TableGroup
+from marker.v2.schema.text import Line, Span
+
+BLOCK_REGISTRY: Dict[BlockTypes, str] = {}
+
+
+def register_block_class(block_type: BlockTypes, block_cls: Type[Block]):
+    BLOCK_REGISTRY[block_type] = f"{block_cls.__module__}.{block_cls.__name__}"
+
+
+def get_block_class(block_type: BlockTypes) -> Type[Block]:
+    class_path = BLOCK_REGISTRY[block_type]
+    module_name, class_name = class_path.rsplit('.', 1)
+    module = import_module(module_name)
+    return getattr(module, class_name)
+
+
+register_block_class(BlockTypes.Line, Line)
+register_block_class(BlockTypes.Span, Span)
+register_block_class(BlockTypes.FigureGroup, FigureGroup)
+register_block_class(BlockTypes.TableGroup, TableGroup)
+register_block_class(BlockTypes.ListGroup, ListGroup)
+register_block_class(BlockTypes.PictureGroup, PictureGroup)
+register_block_class(BlockTypes.Page, PageGroup)
+register_block_class(BlockTypes.Caption, Caption)
+register_block_class(BlockTypes.Code, Code)
+register_block_class(BlockTypes.Figure, Figure)
+register_block_class(BlockTypes.Footnote, Footnote)
+register_block_class(BlockTypes.Form, Form)
+register_block_class(BlockTypes.Equation, Equation)
+register_block_class(BlockTypes.Handwriting, Handwriting)
+register_block_class(BlockTypes.TextInlineMath, InlineMath)
+register_block_class(BlockTypes.ListItem, ListItem)
+register_block_class(BlockTypes.PageFooter, PageFooter)
+register_block_class(BlockTypes.PageHeader, PageHeader)
+register_block_class(BlockTypes.Picture, Picture)
+register_block_class(BlockTypes.SectionHeader, SectionHeader)
+register_block_class(BlockTypes.Table, Table)
+register_block_class(BlockTypes.Text, Text)
+register_block_class(BlockTypes.TableOfContents, TableOfContents)
+register_block_class(BlockTypes.Document, Document)
+
+assert len(BLOCK_REGISTRY) == len(BlockTypes)
+assert all([get_block_class(k).model_fields['block_type'].default == k for k, _ in BLOCK_REGISTRY.items()])
diff --git a/marker/v2/schema/text/__init__.py b/marker/v2/schema/text/__init__.py
index 64015b0d..8901b65f 100644
--- a/marker/v2/schema/text/__init__.py
+++ b/marker/v2/schema/text/__init__.py
@@ -1,8 +1,2 @@
-from marker.v2.schema import BlockTypes
 from marker.v2.schema.text.line import Line
 from marker.v2.schema.text.span import Span
-
-TEXT_BLOCK_REGISTRY = {
-    BlockTypes.Line: Line,
-    BlockTypes.Span: Span,
-}
diff --git a/poetry.lock b/poetry.lock
index e4e8dfcb..c4c900ca 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -1716,6 +1716,21 @@ profiling = ["gprof2dot"]
 rtd = ["jupyter_sphinx", "mdit-py-plugins", "myst-parser", "pyyaml", "sphinx", "sphinx-copybutton", "sphinx-design", "sphinx_book_theme"]
 testing = ["coverage", "pytest", "pytest-cov", "pytest-regressions"]
 
+[[package]]
+name = "markdownify"
+version = "0.13.1"
+description = "Convert HTML to markdown."
+optional = false
+python-versions = "*"
+files = [
+    {file = "markdownify-0.13.1-py3-none-any.whl", hash = "sha256:1d181d43d20902bcc69d7be85b5316ed174d0dda72ff56e14ae4c95a4a407d22"},
+    {file = "markdownify-0.13.1.tar.gz", hash = "sha256:ab257f9e6bd4075118828a28c9d02f8a4bfeb7421f558834aa79b2dfeb32a098"},
+]
+
+[package.dependencies]
+beautifulsoup4 = ">=4.9,<5"
+six = ">=1.15,<2"
+
 [[package]]
 name = "markupsafe"
 version = "3.0.2"
@@ -5208,4 +5223,4 @@ propcache = ">=0.2.0"
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.10"
-content-hash = "87f2bf6e84db6c7100db24777a4104096cb963d9bea7380e520dbc1bd8f2feb7"
+content-hash = "4cb4a1d2f40994498d5657bcb5ab37e7ec9c4bb867015d34131c53000eacfbee"
diff --git a/pyproject.toml b/pyproject.toml
index d2b49103..233e6ecd 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -38,6 +38,7 @@ filetype = "^1.2.0"
 regex = "^2024.4.28"
 pdftext = "^0.3.18"
 tabled-pdf = { git = "https://github.com/VikParuchuri/tabled.git", branch = "dev-mose/compilation-updates" }
+markdownify = "^0.13.1"
 
 [tool.poetry.group.dev.dependencies]
 jupyter = "^1.0.0"
diff --git a/tests/conftest.py b/tests/conftest.py
index 178470a6..31335a1e 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -3,13 +3,17 @@
 
 import datasets
 import pytest
+from typing import Dict, Type
 
+from marker.v2.schema import BlockTypes
+from marker.v2.schema.blocks import Block
 from marker.v2.models import setup_layout_model, setup_texify_model, setup_recognition_model, setup_table_rec_model, \
     setup_detection_model
 from marker.v2.builders.document import DocumentBuilder
 from marker.v2.builders.layout import LayoutBuilder
 from marker.v2.builders.ocr import OcrBuilder
 from marker.v2.schema.document import Document
+from marker.v2.schema.registry import register_block_class
 
 
 @pytest.fixture(scope="session")
@@ -48,13 +52,22 @@ def table_rec_model():
 
 
 @pytest.fixture(scope="function")
-def pdf_provider(request):
+def config(request):
+    config_mark = request.node.get_closest_marker("config")
+    config = config_mark.args[0] if config_mark else {}
+
+    override_map: Dict[BlockTypes, Type[Block]] = config.get("override_map", {})
+    for block_type, override_block_type in override_map.items():
+        register_block_class(block_type, override_block_type)
+
+    return config
+
+
+@pytest.fixture(scope="function")
+def pdf_provider(request, config):
     filename_mark = request.node.get_closest_marker("filename")
     filename = filename_mark.args[0] if filename_mark else "adversarial.pdf"
 
-    config_mark = request.node.get_closest_marker("config")
-    config = config_mark.args[0] if config_mark else None
-
     dataset = datasets.load_dataset("datalab-to/pdfs", split="train")
     idx = dataset['filename'].index(filename)
 
@@ -65,10 +78,7 @@ def pdf_provider(request):
 
 
 @pytest.fixture(scope="function")
-def pdf_document(request, pdf_provider, layout_model, recognition_model, detection_model) -> Document:
-    config_mark = request.node.get_closest_marker("config")
-    config = config_mark.args[0] if config_mark else None
-
+def pdf_document(request, config, pdf_provider, layout_model, recognition_model, detection_model) -> Document:
     layout_builder = LayoutBuilder(layout_model, config)
     ocr_builder = OcrBuilder(detection_model, recognition_model, config)
     builder = DocumentBuilder(config)
diff --git a/tests/test_overriding.py b/tests/test_overriding.py
new file mode 100644
index 00000000..01c4e588
--- /dev/null
+++ b/tests/test_overriding.py
@@ -0,0 +1,49 @@
+import multiprocessing as mp
+
+import pytest
+
+from marker.v2.providers.pdf import PdfProvider
+from marker.v2.schema import BlockTypes
+from marker.v2.schema.blocks import SectionHeader
+from marker.v2.schema.document import Document
+from marker.v2.schema.registry import register_block_class
+from marker.v2.schema.text import Line
+from tests.utils import setup_pdf_provider
+
+
+class NewSectionHeader(SectionHeader):
+    pass
+
+
+class NewLine(Line):
+    pass
+
+
+@pytest.mark.config({
+    "page_range": [0],
+    "override_map": {BlockTypes.SectionHeader: NewSectionHeader}
+})
+def test_overriding(pdf_document: Document):
+    assert pdf_document.pages[0]\
+        .get_block(pdf_document.pages[0].structure[0]).__class__ == NewSectionHeader
+
+
+def get_lines(pdf: str, config=None):
+    provider: PdfProvider = setup_pdf_provider(pdf, config)
+    return provider.get_page_lines(0)
+
+
+def test_overriding_mp():
+    config = {
+        "page_range": [0],
+        "override_map": {BlockTypes.Line: NewLine}
+    }
+
+    for block_type, block_cls in config["override_map"].items():
+        register_block_class(block_type, block_cls)
+
+    pdf_list = ["adversarial.pdf", "adversarial_rot.pdf"]
+
+    with mp.Pool(processes=2) as pool:
+        results = pool.starmap(get_lines, [(pdf, config) for pdf in pdf_list])
+        assert all([r[0].__class__ == NewLine for r in results])
diff --git a/tests/utils.py b/tests/utils.py
index b2e01db5..1f7a2911 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -9,10 +9,10 @@
 from marker.v2.schema.document import Document
 
 
-def setup_pdf_document(
+def setup_pdf_provider(
     filename='adversarial.pdf',
     config=None,
-) -> Document:
+) -> PdfProvider:
     dataset = datasets.load_dataset("datalab-to/pdfs", split="train")
     idx = dataset['filename'].index(filename)
 
@@ -20,11 +20,19 @@ def setup_pdf_document(
     temp_pdf.write(dataset['pdf'][idx])
     temp_pdf.flush()
 
+    provider = PdfProvider(temp_pdf.name, config)
+    return provider
+
+
+def setup_pdf_document(
+    filename='adversarial.pdf',
+    config=None,
+) -> Document:
     layout_model = setup_layout_model()
     recognition_model = setup_recognition_model()
     detection_model = setup_detection_model()
 
-    provider = PdfProvider(temp_pdf.name, config)
+    provider = setup_pdf_provider(filename, config)
     layout_builder = LayoutBuilder(layout_model, config)
     ocr_builder = OcrBuilder(detection_model, recognition_model, config)
     builder = DocumentBuilder(config)