Setting up a multi-signature Bitcoin address with Mycelium 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?
Mycelium does not yet offer that feature:

https://www.reddit.com/r/Bitcoin/comments/41hzan/is_there_a_way_to_sign_a_multisig_transaction/

There are some mobile wallets that offer multisig now:
https://bitcoin.org/en/choose-your-wallet