we have primary (house), secondary (office), and 3 other meet up locations in case things go down when we arent together.

we also have specific markings for each member and markers in each BOB ( 1 in each car, 1 in office, 2 in house)

if we get to meetup and see the mark, we all know who's already been there and to which location they are heading.

if I get to location A and see no marks, I stay put until everyone gets there, etc..