Flutter Using Multiple Models with Scoped Model

I'm trying to build an Expense tracker App in Flutter and has decided to use Scoped Model for state management. The App has a User who can have many Accounts and each account can have many Transactions.

How do I model these to be used with Scoped Model, I am stuck on selecting a good Architecture.

If I create a UserModel that has a list of Accounts where each Account is an AccountModel then triggering and update from inside AccountModel would not trigger the ones accessing the UserModel class.

class CombinedWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final username =
      ScopedModel.of<UserModel>(context, rebuildOnChange: true).username;
    final counter =
      ScopedModel.of<CounterModel>(context, rebuildOnChange: true).counter;

    return Text('$username tapped the button $counter times');

  }
}

you can see complete example in source .