diff --git a/src/ert/config/ensemble_config.py b/src/ert/config/ensemble_config.py
index 91026bde8e6..0908cad5610 100644
--- a/src/ert/config/ensemble_config.py
+++ b/src/ert/config/ensemble_config.py
@@ -152,21 +152,6 @@ def hasNodeGenData(self, key: str) -> bool:
         config = self.response_configs["gen_data"]
         return key in config.keys
 
-    def addNode(self, config_node: Union[ParameterConfig, ResponseConfig]) -> None:
-        assert config_node is not None
-        if config_node.name in self:
-            raise ConfigValidationError(
-                f"Config node with key {config_node.name!r} already present in ensemble config"
-            )
-
-        if isinstance(config_node, ParameterConfig):
-            logger.info(
-                f"Adding {type(config_node).__name__} config (of size {len(config_node)}) to parameter_configs"
-            )
-            self.parameter_configs[config_node.name] = config_node
-        else:
-            self.response_configs[config_node.name] = config_node
-
     def get_keylist_gen_kw(self) -> List[str]:
         return [
             val.name
diff --git a/src/everest/simulator/everest_to_ert.py b/src/everest/simulator/everest_to_ert.py
index 8916f481489..d4dce80ab7f 100644
--- a/src/everest/simulator/everest_to_ert.py
+++ b/src/everest/simulator/everest_to_ert.py
@@ -538,7 +538,7 @@ def _get_variables(
     # configuration key. When initializing an ERT config object, it is ignored.
     # It is used by the Simulator object to inject ExtParamConfig nodes.
     for control in ever_config.controls or []:
-        ens_config.addNode(
+        ens_config.parameter_configs[control.name] = (
             ExtParamConfig(
                 name=control.name,
                 input_keys=_get_variables(control.variables),
diff --git a/tests/ert/unit_tests/simulator/test_batch_sim.py b/tests/ert/unit_tests/simulator/test_batch_sim.py
index 5e961e07db4..dfbbb950163 100644
--- a/tests/ert/unit_tests/simulator/test_batch_sim.py
+++ b/tests/ert/unit_tests/simulator/test_batch_sim.py
@@ -49,21 +49,17 @@ def __init__(self, ert_config, storage, controls, results, callback=None):
         try:
             ens_config = ert_config.ensemble_config
             for control_name, variables in controls.items():
-                ens_config.addNode(
-                    ExtParamConfig(
-                        name=control_name,
-                        input_keys=variables,
-                        output_file=control_name + ".json",
-                    )
+                ens_config.parameter_configs[control_name] = ExtParamConfig(
+                    name=control_name,
+                    input_keys=variables,
+                    output_file=control_name + ".json",
                 )
 
             if "gen_data" not in ens_config:
-                ens_config.addNode(
-                    GenDataConfig(
-                        keys=results,
-                        input_files=[f"{k}" for k in results],
-                        report_steps_list=[None for _ in results],
-                    )
+                ens_config.response_configs["gen_data"] = GenDataConfig(
+                    keys=results,
+                    input_files=[f"{k}" for k in results],
+                    report_steps_list=[None for _ in results],
                 )
             else:
                 existing_gendata = ens_config.response_configs["gen_data"]