Squad Deathmatch - you can lock your squad while users are joining the game

Not sure it is relevant to any of the tags but I noticed when in a game such as squad deathmatch where you're waiting for a few people to join before the match starts, you can go into squad management and lock the squad. If you only have 3/4 people, this means when the 4th squad member joins the game, they are a teammate (blue icon/colour not green) and while they are on your team, on the leader board, they aren't present and I'm not 100% sure if they contribute to your squads overall score but I'm assuming that they can't spawn on you either. I also assume that because they are a teammate and not part of your squad, they can only be revived by medics and other classes can't revive them as they aren't a squad member. A lot of assumptions here as I did it as a test and did not want to actively lock a person out of my squad.

we have 18 kills but only 17 present, the other teammate has 1 kill but can't see him

Ability to lock squad in menu - I did this while 3/4 and when 4th member joined they were locked out from our squad