What I've seen done is this type of setup, is that the co-borrowers who have no "real" interest in the house, sign a quit-claim deed about a week before the property is sold. Are you breaking the mortgage agreement by doing that? Most likely the answer is yes. By the time the bank gets wind of this (which they will immediately after the sale closing) it's a done deal, the property is sold and the bank has nothing to gain by "going after" anyone for potential breach of the loan agreement.
Now how that would work if you live in a community property state, I honestly have no clue if that would even matter.
