Supersig Version 2 Idea (Adding deterministic address to a supersig)

[decentration]

Question: how can we have a deterministic (backup) address for Supersig?

Problem:

• If someone sends funds to a supersig address on a different blockchain, those funds are inaccessible.
• Having a deterministic address for a supersig is useful, even if that address dynamically changes.

Solution:

Supersig has two AccountId's (one Supersig by name, and one multisig backup):

• A supersig AccountId which provably has no private key (like we have now),
  • A name instead of a substrate (hex) address. Why is this important? So that there is no confusion about the address being something you can just send funds to from any chain.
    • The supersig name and location E.g. "ss/KabochaTechTeam", "ss" is the location in the tree for supersigs, and then "KabochaTechTeam" is an example name for a supersig.
• a second "deterministic" address that changes based on adding or removing members to the supersig.
  • This address is a multisig which is created with a fixed threshold ~51% voting, (being number of addresses / 2 + 1).

Benefits of having a multisig backup:

• This address shows up in other blockchains as an accessible and deterministic address.
• This address can therefore be used for balance snapshots (airdrops), and accessible.
• This address can be used on the same chain as a backup (but without Supersig features),
• And for very worst case scenario, just in case Supersig stops functioning properly, and to save from asking democracy to save it.

Possible Collisions:
When creating a supersig (or adding members to a current supersig) the multisig address could clash with an address that is already in storage? (assuming that multisig addresses is generated deterministically by hashing the total addresses + fixed threshold number), what to do:
A) Throw an error, or,
B) Increase the threshold by 1 until there is a free unused multisig available?