The number of drivers depends on the terrain, you want enough drivers to where they are close enough together to allow them to see each other, both for saftey and to keep a deer from slipping through. You want the stander down wind from the deer in a tight funnel area, the drivers should should be up wind of the deer and not make a lot of noise, but just moving at a casual pace, you do not want the deer to panic, you want them simply moving/sneaking out. Great thing you all are doing for your uncle, good luck.