After marriage, the husband and wife use the same property to help their father-in-law repay the mortgage. If both husband and wife are willing, there should be no problem. If one party objects, it can be supported legally, but it seems to be contrary to the traditional family ethics in China.
It is suggested that both men and women fully communicate with the property owner in advance about the payment of mortgage investment, and form a written agreement if they can reach an agreement; If no consensus is reached. Also ask the woman to weigh the pros and cons and properly measure the advance and retreat.