This may be slightly off the 'do-it-yourself' topic but given the family dynamics and depending on budget and tastes within your party, you might consider one of the Japanese steakhouse places ala Benihana or Ron of Japan. It's not first on my list of restaurants to go to, but it does have three elements that might help smooth out the event:
1) The food is squarely middle of the road steak, shrimp, fried rice etc., so everyone should be able to eat decently and you would be hard pressed to say the food was bad.
2) those grill tables are really BIG so you can separate the various factions and give everyone adequate personal space.
3) there is an element of entertainment going on there with the chef/ grillman that is usually pretty humorous and does not require family interaction, though who knows depending on your perspective the family interactions might also provide a degree of entertainment.
Just something to consider.