House hacking a 4plex with only 1/3 of the owners living there?

[Vincent Do]

I have a question about house hacking a fourplex. Does it work when only one of the three owners actually live there? I'm asking because my wife and I are looking to help our son buy a 4plex. He can't qualify on his own, so the wife and I will be on deed and will help with the 20% down payment. Can he reap the benefits of 1st-time home buyer/owner-occupy and we still keep our homestead exemption in our current SFH in this situation? Or is there better way to go about this? Thanks in advance!