http://monerotoruzizulg5ttgat2emf4d6fbmiea25detrmmy7erypseyteyd.onion/resources/user-guides/multisig-messaging-system.html
There are three ways to complete signer information: You can enter it manually, or you can use the auto-config mechanism that the MMS offers, which has a second, "semi-automatic" variant. With 2/2 there is hardly a difference in effort, but with higher numbers of signers auto-config is easier and more reliable. In any case, one advantage of auto-config is a secure transport of addresses because PyBitmessage is used.