In this example, we see updating a record with a key realmId
// Move todo-list into the realm (if not already there):
db.todoLists.update(todoList.id, { realmId });
Is it possible for a record to be in multiple "realms"?
No, a record can only belong to a single realm in Dexie Cloud. But a realm can be shared to many people by adding several "members" that connects the realm to users.