Not meaning to be negative, but from personal experience you may want to have people invite a friend who would be compatible with the group. I unfortunately was part of a group that ran into a problem with open invitation to anyone. The group folded. It started out so wonderfully and ended very badly.
You may want to change to sack lunch with an occasional potluck. Some people just never seem to want to take a turn in the kitchen. People can bring snacks if they wanted to. Years ago I occasionally attended a group who used a local deli to deliver sandwiches which had been ordered earlier in the morning. It helped their business and we could just sew without food prep etc. They also did wonderful lattes.
Sure hope this works out. Nothing is more fun that sewing and visiting with like minded friends. I would hate to see you having to spend the bulk of your time running the group instead of your sewing machine.