Social Security Disability

My 2 children recieve SSD because there dad is disabiled. Up until last month he has recieved the kids money and then gave it to me when he felt like it. I went down and had myself made payee on there money since they live with me full time and rarely see him. Since I did this he has now stop paying me any of the additional money he was paying. His reason is that now that I get the SSD that is his child support.

My questions are:
1-Is this considered child support ( dad also recieves money from 2 other sources), my understanding was that this is my childrens money, not mine or there dads.
2-When I go file for child support is the SSD that my kids recieve considered as part of my income in the calculations of support, or is this left out of mine and his income.

Thank You!