First.... I am sorry you are loosing your home.
I do not know a single bank that will allow this. They generally make you sign arms length transaction meaning you are not related to the person whom is purchasing the home. I have seen banks refuse to sell if the investor was going to rent back the the original owner which in my opinion is going a bit too far but the banks are not happy campers when it comes to this.
If he's going to need a mortgage through a bank in the USA, then is residency status will be an issue plus since you are related, that will be an issue as well. If he's paying cash for it, then you need to contact a realtor to see if there is an issue on that end.
Metlife Home loans
Your easiest and most cost effective way of doing something like this would be to have your relative dedicate the money to you, offer the bank less as a settlement, paying the mortgage off, then doing what ever you and your relative would like to do at that time.
I have had many cases where when a relative came up with a reasonable settlement amount the bank has taken it, you need to avoid having the bank think it is your money and you will need proof that your relative has the money in full.
Buy a home after foreclosure expert