Gamefaqs but PS3 saves you have to use Bruteforce get one of your saves off your PS3 (doesn't matter what game) and use it to transfer your profile over to the other save that you're trying to add then transfer the save you wanted back to your PS3 because PS3 saves are encrypted so Bruteforce can decrypt the save, add your profile then encrypt the save again. I always found it somewhat difficult but was able to successfully do it a few times.
What game?