SPL Token 2022 multisig initialization & update

Question

I want to use multisigs to secure some token / mint operations (like freeze ATAs for example).

To that end, I have two questions:

1. What is the multisig account? Any random PDA account? Nothing is mentioned on the doc so I assume there are no real restrictions, but are there good practices there?
2. Let’s say one of the keys in my multisig definition is lost/compromised. How can I update the multisig to replace it with another one? Can I 'just' delete the PDA, then re-initialize it with the new keys? Obviously in that case that operation would need to be itself protected in the owning program.

Answer 1

So apparently:

1. It can be a PDA, but it doesn’t need to be.
2. It’s just not possible. To achieve that, the best is to put a PDA as the authority and have the program sign with it once it has verified that the instruction was signed with valid signers.

Which means all of this is only as secure as the program itself, so it will need to be either impossible to update, or updated through a multisig (see Snowflake or Squads for example).