My guess is that a 11 and 17 year old will soon get frustrated with being told "no we can't get in line to ride the cosmic master blaster, that you talked about all winter, we have an ADR at Pooh's grand buffet, in 55 mins, so we need to be able to get there so we can eat our chicken and salad".
2TS meals a day will consume well over 4 hours of your time with getting there early for the ADR, waiting, not being able to get in line 30-45 mins prior to the adr time, travel time to the place you are eating.
I urge you to going with one TS a day. I assure you the CS lunch is enough for 2 people. Portions within WDW are much larger then any of us eat while at home.