As of a few days ago, it's been reported that the CS credits for adults and children have not been separated--only the TS have. It is expected that the CS credits will be separated soon.
If they are still pooled when you go, things will work as they always have, and # of meals ordered = # credits deducted.
If they are separated by the time you go, as I understand it, you will be able to order off the regular menu for the kids and pay with child credits. You should not be able to order more than the number of adult and child meals listed on your KTTW card; ie, you will only be allowed a maximum of 2 adult and 2 child meals at any one time. If you only wanted to order 1A/2C or even 2C meals, I would assume they'd have to allow that. I guess we'll find out.