Child Support and Social Security Disability?

My son was disabled before the age of 19. He is now 45 and until last year, when I started drawing SS, he was getting SSI. He is now drawing disability from AD on my work record. He draws half of what I draw. It is about $100 more than he drew on SSI.

He is the noncustodial parent of a 12 year old. He was not required to pay child support out of his SSI check. I have always helped as much as I can with clothes, dance lessons, etc. He barely makes enough to get through the month. Will he now be required to pay support? If he was drawing SS disability off of his own record, I know he would. But he gets much less drawing off of mine.