diff --git a/app/schemas.py b/app/schemas.py
index c79f7517f..7144c6750 100644
--- a/app/schemas.py
+++ b/app/schemas.py
@@ -24,6 +24,7 @@ from app.enums import (
     NotificationStatus,
     OrganizationType,
     ServicePermissionType,
+    TemplateProcessType,
     TemplateType,
 )
 from app.models import ServicePermission
@@ -460,7 +461,7 @@ class TemplateSchemaNoDetail(TemplateSchema):
 class TemplateHistorySchema(BaseSchema):
     reply_to = fields.Method("get_reply_to", allow_none=True)
     reply_to_text = fields.Method("get_reply_to_text", allow_none=True)
-    process_type = field_for(models.Template, "process_type")
+    process_type = SafeEnumField(TemplateProcessType, by_value=True)
     template_type = auto_field(by_value=True)
 
     created_by = fields.Nested(
diff --git a/app/service_invite/rest.py b/app/service_invite/rest.py
index 8a338a77c..1694208b5 100644
--- a/app/service_invite/rest.py
+++ b/app/service_invite/rest.py
@@ -24,7 +24,7 @@ from app.notifications.process_notifications import (
     persist_notification,
     send_notification_to_queue,
 )
-from app.schemas import invited_user_schema
+from app.schemas import InvitedUserSchema
 from app.utils import utc_now
 from notifications_utils.url_safe_token import check_token, generate_token
 
@@ -105,30 +105,30 @@ def create_invited_user(service_id):
         current_app.logger.exception("state not found in submitted data.")
         raise
 
-    invited_user = invited_user_schema.load(request_json)
+    invited_user = InvitedUserSchema(session=db.session).load(request_json)
     save_invited_user(invited_user)
 
     invite_data = _create_service_invite(invited_user, nonce, state)
 
-    return jsonify(data=invited_user_schema.dump(invited_user), invite=invite_data), 201
+    return jsonify(data=InvitedUserSchema(session=db.session).dump(invited_user), invite=invite_data), 201
 
 
 @service_invite.route("/service/<service_id>/invite/expired", methods=["GET"])
 def get_expired_invited_users_by_service(service_id):
     expired_invited_users = get_expired_invited_users_for_service(service_id)
-    return jsonify(data=invited_user_schema.dump(expired_invited_users, many=True)), 200
+    return jsonify(data=InvitedUserSchema(session=db.session).dump(expired_invited_users, many=True)), 200
 
 
 @service_invite.route("/service/<service_id>/invite", methods=["GET"])
 def get_invited_users_by_service(service_id):
     invited_users = get_invited_users_for_service(service_id)
-    return jsonify(data=invited_user_schema.dump(invited_users, many=True)), 200
+    return jsonify(data=InvitedUserSchema(session=db.session).dump(invited_users, many=True)), 200
 
 
 @service_invite.route("/service/<service_id>/invite/<invited_user_id>", methods=["GET"])
 def get_invited_user_by_service(service_id, invited_user_id):
     invited_user = get_invited_user_by_service_and_id(service_id, invited_user_id)
-    return jsonify(data=invited_user_schema.dump(invited_user)), 200
+    return jsonify(data=InvitedUserSchema(session=db.session).dump(invited_user)), 200
 
 
 @service_invite.route(
@@ -139,11 +139,11 @@ def update_invited_user(service_id, invited_user_id):
         service_id=service_id, invited_user_id=invited_user_id
     )
 
-    current_data = dict(invited_user_schema.dump(fetched).items())
+    current_data = dict(InvitedUserSchema(session=db.session).dump(fetched).items())
     current_data.update(request.get_json())
-    update_dict = invited_user_schema.load(current_data)
+    update_dict = InvitedUserSchema(session=db.session).load(current_data)
     save_invited_user(update_dict)
-    return jsonify(data=invited_user_schema.dump(fetched)), 200
+    return jsonify(data=InvitedUserSchema(session=db.session).dump(fetched)), 200
 
 
 @service_invite.route(
@@ -178,14 +178,14 @@ def resend_service_invite(service_id, invited_user_id):
     fetched.created_at = utc_now()
     fetched.status = InvitedUserStatus.PENDING
 
-    current_data = {k: v for k, v in invited_user_schema.dump(fetched).items()}
-    update_dict = invited_user_schema.load(current_data)
+    current_data = {k: v for k, v in InvitedUserSchema(session=db.session).dump(fetched).items()}
+    update_dict = InvitedUserSchema(session=db.session).load(current_data)
 
     save_invited_user(update_dict)
 
     invite_data = _create_service_invite(fetched, nonce, state)
 
-    return jsonify(data=invited_user_schema.dump(fetched), invite=invite_data), 200
+    return jsonify(data=InvitedUserSchema(session=db.session).dump(fetched), invite=invite_data), 200
 
 
 def invited_user_url(invited_user_id, invite_link_host=None):
@@ -204,7 +204,7 @@ def invited_user_url(invited_user_id, invite_link_host=None):
 @service_invite.route("/invite/service/<uuid:invited_user_id>", methods=["GET"])
 def get_invited_user(invited_user_id):
     invited_user = get_invited_user_by_id(invited_user_id)
-    return jsonify(data=invited_user_schema.dump(invited_user)), 200
+    return jsonify(data=InvitedUserSchema(session=db.session).dump(invited_user)), 200
 
 
 @service_invite.route("/invite/service/<token>", methods=["GET"])
@@ -232,7 +232,7 @@ def validate_service_invitation_token(token):
         raise InvalidRequest(errors, status_code=400)
 
     invited_user = get_invited_user_by_id(invited_user_id)
-    return jsonify(data=invited_user_schema.dump(invited_user)), 200
+    return jsonify(data=InvitedUserSchema(session=db.session).dump(invited_user)), 200
 
 
 def get_user_data_url_safe(data):