Thanks to you both for the quick responses! So in short, I've got nothing to worry about for the year of 2017 since we just recently separated, and I can easily provide such proof if requested. Additionally the year my MIL filed 1 our kids and got the EITC she technically should not had been able to.
I also read in my research that in a battle such as this, that the parent will always win, thus my question about the IRS knowing who the immediate parents are. And even the form 8832 is targeted at the parents, which I'm not sure if I could get them to sign if need be, but unsure of why they would need to if they won't be filing taxes.
After court, I am not sure which of us will be the custodial parent. If it is me, then even in the future I've got nothing to worry about. If it isn't me, then I obviously will be referring to this page year after year. Especially since Hal_Al, you're right, that if the other parent got a part-time job, income below the threshold of SSDI limits, they could still try to file, or later in life move and share the same address as the grandmother in question.
Is the rule I read "1. Relationship Test: If only one of the taxpayers claiming the child is the child's parent, then the child will be the qualifying child of the parent." always true? It seems as though maybe it's not based on the answer given.
