I currently have a shared account with my dad with just a cloned copy of the private key and I would like to setup a multi-signature account with him. I'm trying to do this with Mycelium, but I can't seem to figure out how to do it.

My main goal is to be alerted if he spends from the account and I would have to approve of it first and vice versa. When he spends from the account does my wallet get alerted? How does it work on a mobile app?