diff --git a/src/spiffworkflow_backend/models/message_correlation.py b/src/spiffworkflow_backend/models/message_correlation.py
index ec97200b..8ab9f920 100644
--- a/src/spiffworkflow_backend/models/message_correlation.py
+++ b/src/spiffworkflow_backend/models/message_correlation.py
@@ -1,6 +1,8 @@
 """Message_correlation."""
 from dataclasses import dataclass
 
+from sqlalchemy.orm import relationship
+
 from flask_bpmn.models.db import db
 from flask_bpmn.models.db import SpiffworkflowBaseDBModel
 from sqlalchemy import ForeignKey
@@ -36,3 +38,5 @@ class MessageCorrelationModel(SpiffworkflowBaseDBModel):
     value = db.Column(db.String(255), nullable=False, index=True)
     updated_at_in_seconds: int = db.Column(db.Integer)
     created_at_in_seconds: int = db.Column(db.Integer)
+
+    message_correlations_message_instances = relationship("MessageCorrelationMessageInstanceModel", cascade="delete")
diff --git a/src/spiffworkflow_backend/models/message_instance.py b/src/spiffworkflow_backend/models/message_instance.py
index 99556502..bac4eb17 100644
--- a/src/spiffworkflow_backend/models/message_instance.py
+++ b/src/spiffworkflow_backend/models/message_instance.py
@@ -42,6 +42,7 @@ class MessageInstanceModel(SpiffworkflowBaseDBModel):
     process_instance_id: int = db.Column(ForeignKey(ProcessInstanceModel.id), nullable=False)  # type: ignore
     message_model_id: int = db.Column(ForeignKey(MessageModel.id), nullable=False)
     message_model = relationship("MessageModel")
+    message_correlations_message_instances = relationship("MessageCorrelationMessageInstanceModel", cascade="delete")
 
     message_type: str = db.Column(db.String(20), nullable=False)
     payload: str = db.Column(db.JSON)
diff --git a/src/spiffworkflow_backend/models/process_instance.py b/src/spiffworkflow_backend/models/process_instance.py
index ea9fa615..ac0bb315 100644
--- a/src/spiffworkflow_backend/models/process_instance.py
+++ b/src/spiffworkflow_backend/models/process_instance.py
@@ -95,6 +95,8 @@ class ProcessInstanceModel(SpiffworkflowBaseDBModel):
     active_tasks = relationship("ActiveTaskModel", cascade="delete")  # type: ignore
     task_events = relationship("TaskEventModel", cascade="delete")  # type: ignore
     spiff_logs = relationship("SpiffLoggingModel", cascade="delete")  # type: ignore
+    message_instances = relationship("MessageInstanceModel", cascade="delete")  # type: ignore
+    message_correlations = relationship("MessageCorrelationModel", cascade="delete")  # type: ignore
 
     bpmn_json: str | None = deferred(db.Column(db.JSON))  # type: ignore
     start_in_seconds: int | None = db.Column(db.Integer)