The way the system is currently set up, there is no such thing as a "child's" or "adult's" credit. There are table service, counter service, and snack credits. Yes, your KTTW will say "A02 C01 if you are 2 adults with one child, but you do not have to eat together. You do not have "your credits" and "her credits". You have credits.
The requirement on the plan is that IF she orders a meal and a child's menu is available, she orders from the child's menu. At some restaurants, she will be allowed to order an adult entree (Le Cellier, for example.) You can go to dinner without her. Or you can go to dinner with her and feed her off your food--they will bring her own plate. In that case, you will not "spend" that credit. Without getting into the ethics of the issue, you could theoretically share with her at many TS restaurants and end up with "her" credits to use at a 2TS restaurant. They are not listed as "child's" credits and you could choose to use them to pay for your meal.
You can also choose to share CS meals.....again, saving credits to use another day.
Do remember that the plan is subject to change at any time Disney might choose....and a logical change would be to separate child's from adult credits.