Shared AR: Choosing a specific "host"

Hi! I am developing an AR music experience using Shared AR to hold a lobby of people. I am trying to select a specific “host” or “admin” that will be able to view buttons that control the experience. This grid of buttons is hidden for users unless a key-value pair (using roomConnection.roomData and the user’s roomConnection.assignedPeerId) holds a value of “true”.

The problem I am having is that I want to assign a value to a user’s kvp when they join the lobby (in the waiting room). This allows me to check if there’s already an existing admin before deciding whether or not to make that user an admin. I am currently listening to the lobby8-roomJoined event, but it seems that this event is related to joining the AR room-- not the lobby.

Is there any way to process a user as they join the waiting room lobby? Or, is there a way to pick out a specific user as the room is created (assignedPeerIds seem to be randomly generated and the peersInRoom array’s order is different based on the user)?

Note: I don’t want to randomly pick a PeerId-- rather, I want specifically the first user to be the “host” or “admin” (aka the person to start the experience).