From Page 38 of The Hunters Starter Rulebook under Followers:
During the regroup phase, when the Free Peoples player reconciles and minons are discarded, each follower is transferred back to the support area (at no cost).
In later turns, that follower may again be transferred to a companion (the same one or a diiferent one, your choice)
This also suggests to me that followers are only meant to be transferred once per turn.