I've shot many a group with a Yashica D, you just have to get creative. Shot a family for an aniversary, 14 kids on a stone bridge in a city park, around trees, and on a grassy embankment.Largest group was seventy people at a family reunion, Kowa Super 66 with 80 and150mm lenses, loads of smaller groups and such with great grandma on down. Tripod set up in the back of my CJ-7 and went for it. Make sure you take a short step ladder and get the camera high enough to get decent perspective. Heck, get a camera clamp and a tall step ladder and shoot from the top. I've used tarps for scrims to block harsh light, and 4x8 sheets of foil faced rigid insulation board for reflectors. Since you will be shooting where you work, get a bunch of test shots then make a plan. Someone suggested an assistant, great idea. Make sure you inform the group that blinkers buy the beer.