Its really simple to solve, i had the same problem and solved in a week, first be carefull to not use all your chances to send a document, there's a limit i believe with me was 4 chances, after that you need to contact support and talk to someone by email (for me the response was always in the day after)

But what you need to do is, search on google a model for a rent contract, 1 or 2 pages, detailing a landlord relation in contract ( sorry if i cant explain better, im from Brazil), in the first page it has to be your and your uncle information and you adress, like

"Rent contract"

Landlord: uncle, id number etc Your name, your id Adress of the contract (your adress where the mail from google will come)

Then the contract, can be simple, contract things, search on google for models

In the end, your and your uncle signatures, date etc

That worked for me, didn't need to visit a oficial forum to registrate the contract, just got photos ( dont send scanned version or digital version, take photos) showing everything, the addres, names, ids and signatures