NO, not if the child is over 18 and receiving an SSI check.
Yes.
no, as that would create an overpayment.
Yes, If it is back child support than it is already owed. Sorry.
In general, child support is a percentage of net income. When calculating support for younger children, support actually ordered and paid for older children is subtracted from net income.
Get a DNA test. Then if it proves the child isn't yours you won't have to pay child support. You might even be a able to get back the money you have already paid in child support.
The living parent may still be ordered to pay support. Why doesn't the living parent have custody? see link below
If by "back pay" you mean retroactive support, that is typically awarded with the entry of the original order for current support,
her yes, him no.
In most cases the parent who receives the child support is required to file for a modification of the terms in the original order before an increase in support payments is possible.
Yes, until you have filed and had approved an order to modify the existing support order.
Yes, the back support will still be owed, unless the custodial parent agrees to 'forgive' it.
No. If you are not married you pay child support to the custodial guardian, in this case the mother (?), and they take a 26% (?) out of your income to pay for the child. She is also already spending a % of her income. Since you are not married you do not share a income.