I believe the Kenshuusei Unit will add members, much like Ocha and Beyo added - now its a matter of knowing the number and from where (really curious to see if they add more trainees)
But the pattern feels like repeating itself:
Beyo started as 3, added 6 trainees and then 3 auditionees
Ocha started as 4, added 4 trainees and 2 auditionees
Unit started as 5, added 2 trainees and x auditionees??