"is a family member of a more than 2% shareholder in an S Corp"

Okay, so indirect ownership attribution. We would still need more info, such as:

"The above-the-line deduction is not available if the 2% shareholder or spouse is eligible to participate in any subsidized health care plan."

You want to read Form 1040 instructions for Schedule 1 Line 17:

https://www.irs.gov/pub/irs-pdf/i1040gi.pdf