Currently when we have an unincorporated service organization have a change of signers on an account after reviewing the minutes we require all new account documents. We have one organization that the signers change every 6 months. We have been asked if instead of all new documents if we can just remove the people that are no longer authorized and do an addendum to the signature card to add the new signers.
How are other banks handling?

Since you are talking about your legal deposit contract between the bank and the organization and we have no idea how your existing contracts are set up, or what they say, etc., you really need to talk to your legal counsel to get these answers.