diff --git a/noxfile.py b/noxfile.py
index d00df751..416efc67 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -128,6 +128,7 @@ def precommit(session: nox.Session) -> None:
         "lint",
         external=True,
     )
+    session.install("pydoclint")
     session.run("pre-commit", *args, external=True)
     if args and args[0] == "install":
         activate_virtualenv_in_precommit_hooks(session)
diff --git a/src/odoo_data_flow/__main__.py b/src/odoo_data_flow/__main__.py
index fdcf5a2d..b773f72b 100644
--- a/src/odoo_data_flow/__main__.py
+++ b/src/odoo_data_flow/__main__.py
@@ -311,6 +311,11 @@ def import_cmd(connection_file: str, **kwargs: Any) -> None:
     except (ValueError, SyntaxError) as e:
         log.error(f"Invalid --context dictionary provided: {e}")
         return
+
+    groupby = kwargs.get("groupby")
+    if groupby:
+        kwargs["groupby"] = [col.strip() for col in groupby.split(",")]
+
     run_import(**kwargs)
 
 
diff --git a/src/odoo_data_flow/importer.py b/src/odoo_data_flow/importer.py
index dc48e9aa..fbbb0f7a 100755
--- a/src/odoo_data_flow/importer.py
+++ b/src/odoo_data_flow/importer.py
@@ -196,6 +196,23 @@ def run_import(  # noqa: C901
             # Disable deferred fields for this strategy
             deferred_fields = []
 
+    # Filter user-deferred fields to exclude required ones
+    if deferred_fields and model:
+        odoo_fields = preflight._get_odoo_fields(config, model)
+        if odoo_fields:
+            safe_deferred_fields = []
+            for field_name in deferred_fields:
+                clean_field_name = field_name.replace("/id", "")
+                field_info = odoo_fields.get(clean_field_name)
+                if field_info and field_info.get("required", False):
+                    log.warning(
+                        f"Field '{field_name}' is required and cannot be deferred. "
+                        "It will be imported in the first pass."
+                    )
+                else:
+                    safe_deferred_fields.append(field_name)
+            deferred_fields = safe_deferred_fields
+
     final_deferred = deferred_fields or import_plan.get("deferred_fields", [])
     final_uid_field = unique_id_field or import_plan.get("unique_id_field") or "id"
     fail_output_file = str(Path(filename).parent / _get_fail_filename(model, fail))
diff --git a/tests/test_import_threaded.py b/tests/test_import_threaded.py
index 118582a0..71e95b14 100644
--- a/tests/test_import_threaded.py
+++ b/tests/test_import_threaded.py
@@ -661,3 +661,38 @@ def test_recursive_batching_group_col_not_found(self) -> None:
             mock_log.error.assert_called_once_with(
                 "Grouping column 'non_existent' not found. Cannot use --groupby."
             )
+
+    def test_recursive_batching_with_special_chars_in_col_name(self) -> None:
+        """Test batching with special characters in column names."""
+        from odoo_data_flow.import_threaded import _recursive_create_batches
+
+        header = ["id", "name", "partner_id/id"]
+        data = [
+            ["1", "A", "p1"],
+            ["2", "B", "p1"],
+            ["3", "C", "p2"],
+        ]
+        batches = list(
+            _recursive_create_batches(data, ["partner_id/id"], header, 10, False)
+        )
+        assert len(batches) == 2
+        assert batches[0][1][0][2] == "p1"
+        assert batches[1][1][0][2] == "p2"
+
+    def test_recursive_batching_multiple_cols_with_special_chars(self) -> None:
+        """Test batching with multiple columns, one with special characters."""
+        from odoo_data_flow.import_threaded import _recursive_create_batches
+
+        header = ["id", "name", "partner_id/id", "company_id"]
+        data = [
+            ["1", "A", "p1", "c1"],
+            ["2", "B", "p1", "c2"],
+            ["3", "C", "p2", "c1"],
+            ["4", "D", "p1", "c1"],
+        ]
+        batches = list(
+            _recursive_create_batches(
+                data, ["partner_id/id", "company_id"], header, 10, False
+            )
+        )
+        assert len(batches) == 3
diff --git a/tests/test_importer.py b/tests/test_importer.py
index 7df90a20..c0889e4f 100644
--- a/tests/test_importer.py
+++ b/tests/test_importer.py
@@ -380,3 +380,54 @@ def preflight_side_effect(*_args: Any, **kwargs: Any) -> bool:
     )
     mock_import_data.assert_called_once()
     mock_relational_import.assert_not_called()
+
+
+@patch("odoo_data_flow.importer.log")
+@patch("odoo_data_flow.importer.preflight._get_odoo_fields")
+@patch("odoo_data_flow.importer.import_threaded.import_data")
+@patch("odoo_data_flow.importer._run_preflight_checks")
+def test_run_import_does_not_defer_required_fields(
+    mock_preflight: MagicMock,
+    mock_import_data: MagicMock,
+    mock_get_odoo_fields: MagicMock,
+    mock_log: MagicMock,
+    tmp_path: Path,
+) -> None:
+    """Test that a required field is not deferred even if specified by the user."""
+    # Arrange
+    source_file = tmp_path / "source.csv"
+    source_file.touch()
+    mock_preflight.return_value = True
+    mock_import_data.return_value = (True, {"total_records": 1})
+    mock_get_odoo_fields.return_value = {
+        "partner_id": {"type": "many2one", "required": True}
+    }
+
+    # Act
+    run_import(
+        config="dummy.conf",
+        filename=str(source_file),
+        model="res.partner.bank",
+        deferred_fields=["partner_id"],
+        unique_id_field=None,
+        no_preflight_checks=False,
+        headless=True,
+        worker=1,
+        batch_size=100,
+        skip=0,
+        fail=False,
+        separator=";",
+        ignore=None,
+        context={},
+        encoding="utf-8",
+        o2m=False,
+        groupby=None,
+    )
+
+    # Assert
+    mock_import_data.assert_called_once()
+    assert mock_import_data.call_args.kwargs["deferred_fields"] == []
+    mock_log.warning.assert_called_once_with(
+        "Field 'partner_id' is required and cannot be deferred. "
+        "It will be imported in the first pass."
+    )