I shoot large groups outdoors and never use lights, but I have shot in large rooms, considering the hanger of the Enterprise at the Air & Space Museum in Dulles. I used 2 speed lights with large umbrellas for bounce, and let me assure you, those were quite adequate, and they don't allow any electrical cords there. You do with what you have.
Lighting is an art and a science. Let those here help you as many of us have used the equipment we recommend. Some of us can afford very expensive lighting, I cannot. So, I've made up the difference with some skill. Don't underestimate the speedlites.


