I recall seeing some families at the match two years ago accompanying shooters. They weren't following the posses around, but were in the vendor areas while there was shooting going on. I don't know if it was "officially" sanctioned, and they were not in anyone's way. They probably all came together in the same vehicle. Probably best to contact the SASS office and ask them directly.
If you locate Founders Ranch on Google maps you can get an idea of the layout. Basically, it's a row of bays, either 12 or 16, behind which are some permanent buildings for vendors and an additional open area behind them for vendors' tents. Those are in the middle and left side of the bays. The main tent, as well as some other tents are on the right side. Parking is on both sides of the range.
Remember, bring nasal spray to keep sinuses. wet. Very dry there.