Can i (co-signer) or dad (married) do anything to obtain property over a breached contract?

It's very difficult to answer this question without knowing the facts, but generally only parties to a contract can enforce it or seek damages for its breach.  An exception would be if you were what is known as a "third party beneficiary" of the contract.  For this to be the case, the contracting parties must have intended that you receive a direct benefit from the contract, such as a parent's agreement with a pianist to provide piano lessions to her child.  I don't know what type of contract you're talking about, so I can't say whether you were a third party beneficiary, but it's doubtful.  Without more facts, I see no basis for your dad to enforce the contract or sue for damages. The obvious question is why isn't your mother suing for breach?  If it is because she is dead or incapacitated in some way, you or your dad may be able to sue on her behalf.