In the inventory, there is a red diamond on the left of the heading for each character's section, with either a lock icon (only accessible to that player) or a bag icon (accessible to other players). In the controller UI, there is a bag icon (no red diamond) to the right of the characters' portraits, with or without a lock (toggled by the Back button).
Leya will remove the collars for everyone that still has them after completing a task for her. Lohse has a unique dialogue option to be able to get her to do so sooner (and similarly with Beast).
Characters in the same party, with their portrait chained to the leader, will automatically follow the leader.
