IF, however, what you'd like to do is to have your names on the title to the property, you can have your uncle accomplish that quite easily. Check with the escrow officer who handled the purchase and she/he could give you advice to get this done.
And if you want to take over the payments, you can have an agreement in writing between you and your uncle that you are responsible for the mortgage payments. This, however, does not release your uncle from obligations to repay the mortgage as long as only his name is on the mortgage.
Or...as your credit improves and you are paying down your debts, you may qualify to get a mortgage at which point your uncle can attempt to refinance the property with you as the primary borrower.
I believe that the first thing; your Uncle should write a letter to the Lender adding you and your wife, for access to the loan information. They will need his written permission to add you.
Then, if you started making the payments, using your personal checking account, you might get credit for doing so.
After 3-6 months, I would call them and see if your name has been added to loan.
Good luck and may God bless
I would also be careful about messing with the financing or title since your uncle told the lender he was buying it for himself as an investment, unless he put you and your wife on title when he bought it. The mortgage has a due on sale clause if the title changes, good luck,
NMLS # 6395
Financing Kentucky One Home at a Time
He can now deed the property from hisself to all three of you (uncle, you and your wife). This can be done with a Grant Deed. He deeds his title over to all of you.
This should be done sooner than later, as the county will charge you a transfer tax based upon the current value of your home. Talk to the county and ask them how much that will cost. In Alameda county it could cost up to $1.10 per thousand ($220 on a $200k home).
If your plan is to make the payments and then refi two years after the completion of the short sale, you need to be on a title for a minimum of a year to be able to refinance that home in your name. You should be writing the check directly to the bank, as well. You need to establish that you are the owner and the party who has been responsibly paying that mortgage.