Back child support owed

My parents have been divorced for 20+ years. They had us young I’m the oldest 33 and my parents just turned 50.

My dad is an alcoholic/drug addicted recovering relapsing my entire childhood and adult life. He’s been sober the longest for 3yrs. In 2017 he was diagnosed with cancer. He’s currently in jail bc he started doing drugs and broke into a business and stole. He’s in jail and has cancer and most likely dying from the cancer. My mom asked us if we were ok with her writing a letter to our state figuring the back child support. 3/4 said yes. 1 said no bc he’s selfish and had someone else fill out the paper work for the stimulus check (which our state took bc he owes the state) and only mentioned that he was going to get the stimulus when he thought my mom had gotten it instead.

What would you do? Let it go or let it hang over his head? I said let it go even if he wasn’t in jail he’s never pay what he owes anyway.