Just tell him sure he can have 20% and when you cash the check you will give him his share. Get something in writing that says he gets his 20 %. That should make him happy. If You have to put money up than it is a scam. Their are people that search out money that is owed to people that was forgoten. These people have you sign a contract that says that they get their ( finders fee). You get the money that you wouldn't otherwise have. REMEMBER if you have to do anything but sign his fee contract it is a scam. And if it is a large amount of $ - Have your attourney look at the contract.