Add a new message type to record fee payment and initiation
Create a message type specifically for recording payments and recording the initiator. Send this message as soon as the initial signer's threshold is met. Thus the following change to the authority model: once the initial signer's authority threshold is met, the fee is payed and the transaction is initiated, regardless of whether the signature is accepted. The signature may be from an unauthorized authority, or there may be a break in the delegation chain, but the fee will still be paid and the transaction will be initiated.