I was thinking about having my two kids share a TS adult meal but reading these boards it seems as though I can't order more than 2 adult meals at a time if my KTTW card lists 2 A, 3 C.
That is correct. You can only order the number of meals specified on your KTTW card so in your case that would be a maximum of 2 A, 3 C meals at any given time.
If you want to have your kids share an adult meal you could pay OOP for that meal.
You could also call and arrange to have one or more of your kids upgraded to adult status on your resort reservation. He would be listed as ten years old and you would have to purchase an adult MYW ticket for him, but he would qualify for the adult dining plan. If you're getting free dining there would be no additional cost. If you're paying for the dining plan you would have to pay the adult price for him.
If your kids are good eaters, many people have said the children's portions are pretty small and are not enough.
A friend had told me that kids can order off the adult menu at a TS restaurant at LUNCH ONLY and I think she said it would only count as a child TS credit. Can anyone confirm this?