http://monerotoruzizulg5ttgat2emf4d6fbmiea25detrmmy7erypseyteyd.onion/resources/user-guides/multisig-messaging-system.html
You don't have to create signers; after the mms init command they are already all "there", although without any info yet with the exception of yourself. The commands for setting signer information refer to them by number, 1 up to the total number of authorized signers, so 1 and 2 in the following 2/2 multisig example with signers named Alice and Bob and thus with the labels alice and bob .