"doesn't work to generate the married limit ($7,100)" Hmmm...

There is no Married Limit. It's an issue of Plan Coverage. A Single-person with a child can have a Family Plan. A Married Person can have a Single Plan.

Are you trying to get "single x 2" for a Married person, or does your taxpayer who is MFS have a Family Plan insurance policy that also is High Deductible coverage?