It’s okay if they get up and play a little so everyone else can take their time. They’ll sing along to the songs/zmiros they like/know so you can incorporate some age appropriate favorites.
Review the school “Shabbos” stuff if they have any, but don’t “farher” unless you know they’re comfortable with it. They should be at the table to eat and join in as much as feasible, but don’t turn it into some tug of war.
As someone wise said something along the lines of “although you’ve probably forgotten, you also ran off and played when you were their age, so don’t worry about it, they’ll grow out of it too”.
Bottom line, involve them as much as possible — short stories are great — but don’t stifle the adults either.