self.description.save(db_conn)
         assert isinstance(self.id_, int)
         db_conn.cached_conditions[self.id_] = self
+
+
+class ConditionsRelations:
+    """Methods for handling relations to Conditions, for Todo and Process."""
+
+    def set_conditions(self, db_conn: DatabaseConnection, ids: list[int],
+                       target: str = 'conditions') -> None:
+        """Set self.[target] to Conditions identified by ids."""
+        target_list = getattr(self, target)
+        while len(target_list) > 0:
+            target_list.pop()
+        for id_ in ids:
+            target_list += [Condition.by_id(db_conn, id_)]
+
+    def set_enables(self, db_conn: DatabaseConnection,
+                    ids: list[int]) -> None:
+        """Set self.enables to Conditions identified by ids."""
+        self.set_conditions(db_conn, ids, 'enables')
+
+    def set_disables(self, db_conn: DatabaseConnection,
+                     ids: list[int]) -> None:
+        """Set self.disables to Conditions identified by ids."""
+        self.set_conditions(db_conn, ids, 'disables')
 
 from typing import Any, Set
 from plomtask.db import DatabaseConnection, BaseModel
 from plomtask.misc import VersionedAttribute
-from plomtask.conditions import Condition
+from plomtask.conditions import Condition, ConditionsRelations
 from plomtask.exceptions import NotFoundException, BadFormatException
 
 
-class Process(BaseModel):
+class Process(BaseModel, ConditionsRelations):
     """Template for, and metadata for, Todos, and their arrangements."""
     table_name = 'processes'
 
             walk_steps(step_id, step_node)
         return steps
 
-    def set_conditions(self, db_conn: DatabaseConnection, ids: list[int],
-                       trgt: str = 'conditions') -> None:
-        """Set self.[target] to Conditions identified by ids."""
-        trgt_list = getattr(self, trgt)
-        while len(trgt_list) > 0:
-            trgt_list.pop()
-        for id_ in ids:
-            trgt_list += [Condition.by_id(db_conn, id_)]
-
-    def set_enables(self, db_conn: DatabaseConnection,
-                    ids: list[int]) -> None:
-        """Set self.enables to Conditions identified by ids."""
-        self.set_conditions(db_conn, ids, 'enables')
-
-    def set_disables(self, db_conn: DatabaseConnection,
-                     ids: list[int]) -> None:
-        """Set self.disables to Conditions identified by ids."""
-        self.set_conditions(db_conn, ids, 'disables')
-
     def _add_step(self,
                   db_conn: DatabaseConnection,
                   id_: int | None,
 
 from sqlite3 import Row
 from plomtask.db import DatabaseConnection, BaseModel
 from plomtask.processes import Process
-from plomtask.conditions import Condition
+from plomtask.conditions import Condition, ConditionsRelations
 from plomtask.exceptions import (NotFoundException, BadFormatException,
                                  HandledException)
 
 
-class Todo(BaseModel):
+class Todo(BaseModel, ConditionsRelations):
     """Individual actionable."""
 
     # pylint: disable=too-many-instance-attributes
                 for condition in self.disables:
                     condition.is_active = False
 
-    def set_disables(self, db_conn: DatabaseConnection,
-                     ids: list[int]) -> None:
-        """Set self.disables to Conditions identified by ids."""
-        self.set_conditions(db_conn, ids, 'disables')
-
-    def set_enables(self, db_conn: DatabaseConnection,
-                    ids: list[int]) -> None:
-        """Set self.enables to Conditions identified by ids."""
-        self.set_conditions(db_conn, ids, 'enables')
-
-    def set_conditions(self, db_conn: DatabaseConnection, ids: list[int],
-                       target: str = 'conditions') -> None:
-        """Set self.[target] to Conditions identified by ids."""
-        target_list = getattr(self, target)
-        while len(target_list) > 0:
-            target_list.pop()
-        for id_ in ids:
-            target_list += [Condition.by_id(db_conn, id_)]
-
     def add_child(self, child: Todo) -> None:
         """Add child to self.children, guard against recursion"""
         def walk_steps(node: Todo) -> None: