Alright guys. Since my last reply, I'm happy to note that we've grown to around 60 members.
Now...if we are truly going to dwell on this, then here is my answer: This group was named FRC Captains Round Table, SIMPLY BECAUSE IT SOUNDS COOL LIKE THAT.

You know....Knights of the Round Table sort of thing....
Also, say you are given the title Team President, Team Leader, Principal Lead Student, CEO, or anything else that is the equivalent of a Team Captain, then you are
DEFINITELY ALLOWED TO JOIN. People who have held the title in the past are also allowed to join the group.
I will stress that this group will not let in: Coaches, Team parents, any student who isn't Captain or the equivalent (which includes sub division heads etc), or Mentors (unless they were captain or the equivalent in the past).
This will not be a group for general student leaders within the team, and if anyone wants to make that happen, by all means please start a group for that and I would love to join. This group, is for the afore mentioned list of Team Leaders.
I hope this helps in everyone's understanding!