Some sort of paper trail is always handy, especially when its ownership is shared, such as email records. Band rules and communication are a pre-requisite. If there is a person who is going to speak for the band in financial or scheduling matters, that person needs to be established as the designated representative. All negotiation attempts should be directed to that person representing the group response, who in turn speaks for the band consensus. If someone wants to negotiate a pay cut for the band outside of that structure, they are welcome to do so out of their own share.