Follow all the same steps for setting up the wallet key, except you want to saw you have a SEED to get started with.Then I think you might need to enter the other 4 public seeds which you should have from when we started the wallet initially ( @Kieran here's another thing people are going to lose and it might be good to back up ... maybe this process for multisig wallets actually extends quite far out to where the seed came from ... and the data also relevant to it... like all the other seeds needs. But this could be an advanced case)