How to report inherited IRA basis.

My wife passed away in 2020 so I inherited her IRA. She had basis in her IRA due to non-deductible contributions. I made withdrawals from that IRA in 2020 and received a 1099-R. I also have my own IRA with basis. I filed married filing joint in 2019 and filed form 8606 for each of us.

How do I handle the transfer of my wife’s basis to me?