diff --git a/alembic/versions/95d8b982cd5d_add_nma_chemistry_lineage_relations.py b/alembic/versions/95d8b982cd5d_add_nma_chemistry_lineage_relations.py
index b6b2b213f..c9f6a79e3 100644
--- a/alembic/versions/95d8b982cd5d_add_nma_chemistry_lineage_relations.py
+++ b/alembic/versions/95d8b982cd5d_add_nma_chemistry_lineage_relations.py
@@ -29,10 +29,10 @@ def upgrade() -> None:
     inspector = inspect(bind)
     columns = {col["name"] for col in inspector.get_columns("NMA_Chemistry_SampleInfo")}
     if "thing_id" not in columns:
-        # Add thing_id FK to NMA_Chemistry_SampleInfo (NOT NULL - no orphans)
+        # Add thing_id FK to NMA_Chemistry_SampleInfo (nullable to allow legacy orphans)
         op.add_column(
             "NMA_Chemistry_SampleInfo",
-            sa.Column("thing_id", sa.Integer(), nullable=False),
+            sa.Column("thing_id", sa.Integer(), nullable=True),
         )
 
     existing_fks = {
diff --git a/db/nma_legacy.py b/db/nma_legacy.py
index 14cd9b728..053276af0 100644
--- a/db/nma_legacy.py
+++ b/db/nma_legacy.py
@@ -173,7 +173,7 @@ class ChemistrySampleInfo(Base):
         "SamplePointID", String(10), nullable=False
     )
 
-    # FK to Thing - required (no orphans)
+    # FK to Thing - required for all ChemistrySampleInfo records
     thing_id: Mapped[int] = mapped_column(
         Integer, ForeignKey("thing.id", ondelete="CASCADE"), nullable=False
     )