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First, look at the upper right hand corner and be sure the letter is from 2022, as sometimes they are for the previous year.

It sounds like you entered the Form 1095-A and generated a Form 8962 in both your return and your non-dependent child's return. 
Since your child's refund was processed and the letter came to you, they should have stated what they needed you to return to them for processing. 

If it is unclear, I would recommend to call the number in the letter, for that department, and ask them what they need.
If that is not an option, then send them the original Form-1095A and a copy of your child's Form 8962.

For the Part IV that has 1.0, is that in column's e, f, and g?  If I enter something other than 1.0, I get this pop up, so 1.0 sounds fine for that entry.