This intermediate agreement is only partially binding. The property right of the house belongs to three people, so the sale must be approved by his son. If his son doesn't come back to sign, let him write a certificate of consent to the sale, and then go through the formalities, otherwise the house will easily go wrong in the end. Even if the contract is signed, the property owner will have disputes because there is no residence, which is still very troublesome. Although it is effective now, it is also prone to problems.