If you're talking about 2 people being linked to a single car then that's possible, with two separate accounts without any logging in/out faff. We've done this with me and the wife.
1.Ensure your account is linked to the car.
2.Get daughter to download the app on her phone and register an account.
3.Log into your account on your app.
4.Go to settings (circle in bottom right), then 'second account'.
5.Click '+' and fill in her details.
From memory there's an option to allow the second person different levels access. My wife can do all the normal things I can like preheat, see car status, location etc.