Medical premiums for non dependent

My son turned 25 in 2021 and he earned about 38,000 in 2021 and is not disabled or married,but I pay his and ours medical premiums out of pocket through our pension. I know he doesn’t qualify as a qualified relative normally, but I’m getting mixed information about him being able to qualify as a dependent for medical expenses because he’s wasn’t 26 and 26year olds can still be on parents medical. 

I also read section213a, which modifies section 152 and as a result it allows you to take medical tax deduction for a person making more than the 4300.00 income limit as long as you provide half of their support.

1.WELL how do you document/prove that.?

2.Can someone clear this up? Can I claim my medical premiums on my

tax return on schedule A for him or not?