I'm glad the example worksheets helped you. This website has been created to do exactly that - help others learn the in's and out's of child support. We always appreciate feedback on the tools/calculators/forms, as well as the information provided here (in general). It is definitely used to help others like yourself.
I can't be of too much assistance on the different types of medical coverage and payment as I'm not all too familiar with it, but a couple questions come to mind. 1) Where does the money, which you have deposited into your medical spending account, go at the end of the year if no one uses it? 2) If you have a paycheck stub showing you are depositing money into a medical account for your kids, is that not proof enough? If I am thinking of this plan correctly, the reason you have money withheld for this account is because it is tax-exempt, correct?
So, if you were to withhold $100, and you and your ex's portion of the medical care is $120, you would have to pay an additional $20, but that $20 would not be tax-exempt, so you have essentially paid more. Think about child support. Child support is not tax-exempt money for you. So it may be a tax benefit for you handle the healthcare. But, you have to be creative to determine the amount of credit. Obviously you want to aim high. So you can say that you'll withhold $400/mo for the kids (and you start off doing that), but if you find that $4,800/yr is not being used, you can reduce it, and if there ever comes a time, when its needed, you'll have to caugh it up. But, your child support has been adjusted already to account for the $400/mo. I hope that's somewhat a clear thought - I think your plan can work to your benefit it argued and managed correctly.
This is obviously a case where you and your ex need to exchange medical benefits information to best ascertain which plan would be the most cost effective. If your kids are not accident prone and are rarely sick, your plan may be best, but if this is not the case, your ex's plan may be more cost effective.
Here's a few more tips - the medical insurance you are responsible for is the difference between the single plan and the family plan for your ex. So if the single plan is $200, and the family plan is $400, you are only responsible for $200/mo, not the full $400. You are not paying for your ex's insurance. Also, any plan information or proof of payment needs to go both ways. Just because your ex's attorney says so, does not make it fact. You have the same right to see proof that your ex's medical plan premiums are exactly what she says they are. This is only fair to everyone.