Legal Question in Real Estate Law in Massachusetts

The quick answer is yes. The more complicated answer is that a buyer would have to (and should) demand that all owners sign. If a buyer doesn't insist on that at the purchase and sale stage, they may get all the way to closing before they realize one of the sellers isn't cooperating. If you don't have all owners agreeing to sell to you, you don't really have an agreement. Your question makes me think you should have an attorney on this transaction.