Although I am not a mortgage expert, I have helped multiple buyers & sellers deal with 2nd homes. Not being sure exactly what you are concerned about, I'll answer this a couple of ways. Last month we had a closing on a property where the owner was going to put his brother in the new home and keep his. In order to get approved, the mortgage lender asked us to pull rental comps in the area. He entered that amount as positive income which qualified him to purchase the new house. I don't know the lender rules in California, but if you are buying a 2nd home here, they usually require 10% down. Hope this helps. If you need help selling your house, I would love to come talk to you!