Can the child pay for the child support owed by the parent when they turn 18?

My dad owes back child support cuz hes unable to work due to his back i cant find anything to help remove back child support so i was wondering if i cld help pay for it i love my dad and hes under a lot of stress due to him going to court over this ,the doctors cant figure out how to make the pain go away , plus hes trying to raise his 2 kids he had with my stepmom with her little income hes always stressed and in pain so i never get to see him so i was wondering if i cld pay the child support to relieve some of the stress so that maybe hed let me come see him again please help