Co-owned Rentals Deduction Options?

I co-own a few rentals w/ each of my 3 sons.

Most mortgages are NOT in my name on the co-owned properties. However 1 property had a 2nd in my name. That property was sold this year.

Anybody know where I can reseach my options for:

1. Sold co-owned rental options (long term gains)
2. Current options on deductions.

Again, I am trying to find what the IRS demands, requires, and/or suggests. Have not found this info.

Thanks.