diff --git a/event_session/migrations/15.0.1.0.0/pre-migration.py b/event_session/migrations/15.0.1.0.0/pre-migration.py
new file mode 100644
index 000000000..53b599f9a
--- /dev/null
+++ b/event_session/migrations/15.0.1.0.0/pre-migration.py
@@ -0,0 +1,36 @@
+# Copyright 2012 Tecnativa - David Vidal
+# License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl).
+from openupgradelib import openupgrade
+
+
+def _set_use_sessions_flag(env):
+    """Preset the new use_sessions flag according to existing data"""
+    openupgrade.logged_query(
+        env.cr, "ALTER TABLE event_type ADD COLUMN IF NOT EXISTS use_sessions BOOLEAN"
+    )
+    openupgrade.logged_query(
+        env.cr, "ALTER TABLE event_event ADD COLUMN IF NOT EXISTS use_sessions BOOLEAN"
+    )
+    openupgrade.logged_query(
+        env.cr,
+        """
+        UPDATE event_event SET use_sessions = true
+        WHERE id in (
+            SELECT DISTINCT event_id FROM event_session
+        )
+    """,
+    )
+    openupgrade.logged_query(
+        env.cr,
+        """
+        UPDATE event_type SET use_sessions = true
+        WHERE id in (
+            SELECT DISTINCT event_type_id FROM event_event WHERE use_sessions
+        )
+    """,
+    )
+
+
+@openupgrade.migrate()
+def migrate(env, version):
+    _set_use_sessions_flag(env)