Microsoft has confirmed (opens in new tab) a rumored Xbox Game Pass family plan by announcing early testing for the program in Colombia and Ireland. 

As of today, Xbox Insiders in Colombia and Ireland can preview a new plan that lets up to five users share the same Xbox Game Pass subscription. Any accounts added by the main user will have “their own unique access to Xbox Game Pass Ultimate games, content, and benefits,” seemingly preventing any bottlenecks for multiple users playing at the same time. You should in theory be able to play Halo Infinite campaign co-op via one Xbox Game Pass subscription, for example.