Session participation in online content streams or activities like multiplayer games is enhanced through management of session tracking and automated queuing of players via a central system between host/streamer client device and guest player client devices. Spectators viewing a content stream or waiting to join a multiplayer activity over a network via a game/streaming service request to be placed in a queue to participate in a session of the content stream or activity as guest players with the host/streaming user. Sessions are tracked to determine start and end events. Sets of prior guest players are removed from sessions when the sessions end, and sets of queued spectators are automatically added to the start of a new session of the content stream or activity as guest players. Queuing may be automatically prioritized for users based on user characteristics, and guest players removed at the end of sessions may be automatically re-queued.