The fork has its own hero section — named, attributed, members shown. It's a first-class object, not a footnote.

The "Rejoins main plan" section shows where the fork converges back. The main itinerary item is visible from inside the fork.

"Join this fork" is available to anyone — forks are open by default. The group can see where everyone is.

"Merge to main" promotes the fork's items back to the main itinerary — for when the rogue plan turns out to be the one everyone wanted.