A single signature hierarchical deterministic wallet has an xpub that allows for viewing of all public addresses derived from the seed but this isn't the case for a multisig. For example a 2 of 3 multisig has 3 individual public keys but no master xpub.
Why is there also not a corresponding xpub that is created from all 3 keys?
And since there isn't an xpub from the 3 keys how are future addresses predictably knowable?