@Bagmanss - Your post is confusing - and many don't understand how the stimulus and Recovery Credits work - it is possible that your ex-DIL has the stimulus but you have the Recovery Credit - and THAT IS HOW IT WORKS
if your ex-DIL received the stimulus for the child, then she keeps it. That is the law. the sti,mulus was an ESTIMATE of what everyone was to receive and was based on 2019 tax filings (or 2018 if 2019 wasn't available)
HOWEVER
these payments were 'an advance against 2020' tax return. That means that the IRS is using 2020 tax return (dependents, income, etc.) to determine what everyone is ACTUALLY due.
if that ACTUAL is more than the ESTIMATE then the difference is the 'recovery credit' and you will see this on Line 30.
if the ESTIMTE is more than the ACTUAL then there is no additional payment due and Line 30 will be zero; it doesn't have to get paid back, meaning Line 30 can NEVER be negative.
So for your situation,
if I assume that the ex-DIL claimed your grandson in 2019 but you claimed him in 2020, here is what occurred. DID SHE ALSO CLAIM THE CHILD IN 2020? is that the issue?
for the ex-DIL, she ESTIMATE is $1100 - as she got the two stimulus payments for the grandson, but her ACTUAL is zero. She gets to keep the $1100 and Line 30 is zero.
for you, your estimate is zero, but your ACTUAL is $1100, because you are claiming the grandson in 2020. Your Line 30 is $1100.
if you read through that, yes, it does mean the IRS is paying out $2200 for one child.... That is the way it works.