diff --git a/target_salesforce_v3/client.py b/target_salesforce_v3/client.py
index 57e8732..6400fc6 100644
--- a/target_salesforce_v3/client.py
+++ b/target_salesforce_v3/client.py
@@ -225,6 +225,7 @@ def sf_fields_description(self, object_type=None):
             if not f["nillable"] and f["createable"] and not f["defaultedOnCreate"]
         ]
         fields["external_ids"] = [f["name"] for f in fld if f["externalId"]]
+        fields["idLookup"] = [f["name"] for f in fld if f["idLookup"] == True]
         fields["pickable"] = {}
         for field in fld:
             if field["picklistValues"]:
diff --git a/target_salesforce_v3/sinks.py b/target_salesforce_v3/sinks.py
index 2821c18..8c80185 100644
--- a/target_salesforce_v3/sinks.py
+++ b/target_salesforce_v3/sinks.py
@@ -460,11 +460,12 @@ def reference_contacts(self):
         return [{k: v for k, v in r.items() if k in ["Id", "Name"]} for r in response]
 
     def preprocess_record(self, record, context):
-
-        installment_period = record.get("installment_period").title()
-        installment_period = self.get_pickable(
-            installment_period, "npe03__Installment_Period__c"
-        )
+        installment_period = None
+        if record.get("installment_period"):
+            installment_period = record.get("installment_period").title()
+            installment_period = self.get_pickable(
+                installment_period, "npe03__Installment_Period__c"
+            )
 
         fields_dict = self.sf_fields_description()
         if record.get("created_at"):
@@ -710,25 +711,6 @@ def get_fields_for_object(self, object_type):
 
         raise MissingObjectInSalesforceError(f"Object type {object_type} not found in Salesforce.")
 
-    def validate_record(self, record, fields):
-        new_record = {}
-        for original_field, value in record.items():
-            if original_field not in fields:
-                self.logger.warning(
-                    f"Field {original_field} not found in Salesforce. Will not be synced."
-                )
-                continue
-
-            if fields[original_field]["nillable"] == False and value is None:
-                self.logger.warning(
-                    f"Field {original_field} is not nullable. Will not be synced."
-                )
-                continue
-
-            new_record[original_field] = value
-
-        return new_record
-
     def preprocess_record(self, record, context):
         # Check if object exists in Salesforce
         object_type = None
@@ -751,7 +733,6 @@ def preprocess_record(self, record, context):
         except MissingObjectInSalesforceError:
             self.logger.info("Skipping record, because it was not found on Salesforce.")
             return
-        record = self.validate_record(record, fields)
         record["object_type"] = object_type
         return record
 
@@ -763,12 +744,17 @@ def process_record(self, record, context):
             self.logger.info(f"Processing record for type {self.stream_name} failed. Check logs.")
             return
 
-        required_fields = []
+        fields_desc = self.sf_fields_description(object_type=object_type)
+
+        possible_update_fields = []
+
+        for field in fields_desc["external_ids"]:
+            if field in record:
+                possible_update_fields.append(field)
+
         if record.get("Id"):
             fields = ["Id"]
         else:
-            fields_desc = self.sf_fields_description(object_type=object_type)
-            required_fields = fields_desc["required"]
             list_fields = [field_list for field_list in fields_desc.values()]
             fields = []
             for list_field in list_fields:
@@ -794,16 +780,31 @@ def process_record(self, record, context):
                 response = self.request_api("PATCH", endpoint=url, request_data=record)
                 id = response.json().get("id")
                 self.logger.info(f"{object_type} updated with id: {id}")
+                return
             except Exception as e:
                 self.logger.exception(f"Error encountered while updating {object_type}")
                 raise e
 
-        else:
-            try:
-                response = self.request_api("POST", endpoint=endpoint, request_data=record)
-                id = response.json().get("id")
-                self.logger.info(f"{object_type} created with id: {id}")
-            except Exception as e:
-                self.logger.exception(f"Error encountered while creating {object_type}")
-                raise e
+        if len(possible_update_fields) > 0:
+            for id_field in possible_update_fields:
+                try:
+                    url = "/".join([endpoint, id_field, record.pop(id_field)])
+                    response = self.request_api("PATCH", endpoint=url, request_data=record)
+                    id = response.json().get("id")
+                    self.logger.info(f"{object_type} updated with id: {id}")
+                    return
+                except Exception as e:
+                    self.logger.exception(f"Could not PATCH to {url}: {e}")
+
+        try:
+            if len(possible_update_fields) > 0:
+                self.logger.info("Failed to find updatable entity, trying to create it.")
+
+            response = self.request_api("POST", endpoint=endpoint, request_data=record)
+            id = response.json().get("id")
+            self.logger.info(f"{object_type} created with id: {id}")
+            return
+        except Exception as e:
+            self.logger.exception(f"Error encountered while creating {object_type}")
+            raise e