If Zhang San wrote Li Si's name when he bought a house, and he wrote Li Si's name first on the premise that Zhang San broke his promise, it means that Zhang San may have broken his promise, and he may ask Li Si to change it for him when he can't pay back the money.
Who is the owner of his house? If he can't pay the loan, who will he turn to? If you become the owner of his house, then if he doesn't pay his mortgage, the bank will find you and ask you to pay his mortgage.