You say you support the children. That's not enough. The children must live with you, to be claimed as a dependent.

and "Primary" income is not the same as "only" income.

she does live with me and disability is my only income

@joeahamilton You are posting to someone else's year old thread.  If you are in a similar situation--grandparent supporting a grandchild--if your only income is disability then you cannot get any of the child-related credits like earned income credit or child tax credit which are based on income earned from working.

Even if the parents are sending any child support, it would not need to be reported on a tax return.

The money you hear about people getting for just filing a tax return claiming kids requires you to  have some earned income (wages or self employment). Without earned income, you are not eligible for the "refundable" Earned Income Credit or Additional Child Tax Credit.

@xmasbaby0  Actually, I was thinking that the parents might have hired Grandparent as a Nanny or Household Employee.

Thank you, that's what I was thinking

Baby sitting your grand kids doesn't make them a dependent  or qualifying child for refundable credits. So, what's the real tax question, if it's not about claiming the children as dependents?

Grandparents are exempt from the "nanny tax", unless the parent claims the dependent care credit.  So, you do not have to report any baby sitting income, form sitting you own grandkids.