With your grandkids onboard there is no question except to go to Levick on Friday for the BBQ and The Jumbies, which they will love. Stopping at the Dogs is always dependable on the weather, but if you make an early start, then The Baths is a great place to visit. Bear in mind that this is a busy weekend in BVI, especially North Sound with the Poker Run taking place on Sunday. Check out their website for details. Lots of fast boat throughout the islands, but they come and go very quickly!
Sand Box is an ideal stop for lunch as is Saba Rock, though others may chip in here.
There are always very mixed reviews of Pussers at Marina Cay. If conditions are good, Cooper has excellent food or Last Resort, Bellamy Cay in Trellis Bay could be another option. Always be flexible and keep your options open. You're on vacation and weather and sea conditions must be taken into account. Are you intending to have all meals ashore?