Whenever I pin something down that has to allow for movement I make one of the holes with no allowance for movement. In this case I would make the back attachment solid and the ones going forward to allow movement. This keeps the back edge flush. If I were pinning a breadboard end on a table I would make the center attachment solid and let the rest move from the center going outward either way. That way if the end was shorter or longer because of seasonal movement at least it would be equal on both sides instead of possibly being all on one side.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.