This person bought a condo in 2006. His son co-signed on the mortgage, and both them began to live in it until the son got married and moved out in 2011. In 2019 the condo was sold, and the 1099S is in the son's name with his social security number, so my question is as follows:

1.Since the 1099 S is in his son's name, is he liable for the entire sale?

2. If he is liable for the entire sale, then he will have to pay capital gains on the entire net since the 5 of the 2 yrs does not apply, am I correct?

3. Should he get the 1099 S changed to his father's name since he was the actual owner of the condo and not his son? By the way the father was still living in the condo when it was sold.

4.If they decided to treat the sale as 50% ownership to each other, then I would assume that the father can take the exclusion but the son would not be able to take his exclusion too since he was not living there in last five years before the sale, am I correct?

Thanks