I was at 7Springs the first weekend of Jan. with my son's family including the three grandkids. Found the place in great shape and filed a report in the Locak Resorts Discussion thread on the DCSki forum, Jan 6, call "Mini 7Springs Trip Report". Take a look.
Bottom line, the Tiny Tots Ski School was great and very well run. Thus no real problem keeping track of the kids. Now with the ages of your kids, you will have a problem of keeping track of them both in the lodge and on the slopes. I suggest the Motorola type walkie talkies with a bit of signal distance and multiple channels and subchannels. And you might have set meeting times and places for lunch, snacks, etc. but you will all be spending a lot of time waiting while the various family members underestimate the amount of time it takes to get to the meeting place.
Not sure this helps, GOOD LUCK!