"Lock squad" - some parts could be default - but you "lock" a squad and if team balanced for next round, whole squad flips teams, not just 1-2 guys.
Also when 3 could lock to save spot for 4th. To join a "locked" squad either approve or invite or 2 digit code.

Social playing is chore, play with good squad of 4 and every round part of team gets kicked to other team or squad etc.