Plan shared workouts within Join

It would be a strong addition if Join allowed users to plan shared workouts with their connections or within a group.

Concretely, Join would schedule one workout (for example a long endurance ride) that automatically appears in the training plans of all selected participants. This removes the need to coordinate externally and makes training together much easier.

This feature would be especially valuable for training groups, club mates, or friends who regularly train together.