"Maybe I'm not understanding the stimulus payment but I do accept your answer."

It's become obvious no one understood how to execute this, because they were only able to use old tax returns. That's why people dead in 2019 got stimulus checks based on 2018 tax returns.

"Another person responded to be (I copied their response below). It confused me because they really didn't help but I felt they were telling me I should not allow the mother to collect additional monies."

That's not what I showed. You need to read those links, go to the source which is IRS, and learn the rules that apply to the scenario. That's how you learn it, and don't need to keep asking people on the internet. Or, at the least, you have the ability to check that they are giving you the right guidance, because you check for yourself, as part of this being your responsibility as the tax preparer.

Here's what happened:

 Anyone getting the money for 2020 did not get it based on their 2020 tax return status. You know this. The 2020 tax returns were not yet filed. There is no provision that makes anyone pay anything back. That father got the money as a projection and that projection is not the 2020 reality.

Right now, you are working on the 2020 reality.