Need team leader to answer a question

How do you know who is not being active on your team? When I look at my team, some do not show skulls by their name and I know they have shared skulls with me and should have skulls. I also have team players not on my friend list. Does this mean they added themselves to my team? Since they aren't on my friend list, I can't message them for a skull count update.

Our team needs another player pushing for the game, but I am not sure who to kick as inactive because I can't find a skull count for some.