I mean... Is that someone owner of the 3 houses or just a guest? You would have to consider that first. If you are SURE that he's the owner, basically you can't do it as he already owns 3 houses. BUT IF HE'S A GUEST, then you technically could. You could make someone a GUEST on a 1,000 houses if you wanted to, But ownership it's a whole different issue. TALK TO HIM :)