Again, thank you for taking the time. I am almost there!
If she is not eligible for a Roth, it sounds like you believe that her best option is a non deductible contribution for 2021. Is this correct and I assume that she can make it now if she wants.
To your last paragraph. When I wrote “Since there is still a possibility (I think remote) that she would be eligible for a Roth IRA, can the decision wait until just before she files her 2021 taxes?, what I mean is can she wait until 2021 taxes are calculated to make the 2021 contribution.