The upcoming cook-off will be my first luggable loo large group camping. Alone and small group, I usually rig a privacy tarp with an indicator for in use, but guys urinate in the bushes, so the gelling agent is conserved for women, and not have to use as many bags.
This does not sound like a family friendly approach for large group, so what is proper etiquette?
Set up near your camp. Sounds like you may not have one so a bathroom/shower tent would be a good idea for privacy. They can be very inexpensive. I think mine was $30
More about where to set up your own and such
There is no expectation to share toilet facilities in the wilderness.