Extended from comment on another suggestion:

Problem: It is currently very difficult to trigger a single event from a set.

Use-case: I had a looping step that I wanted to add some more randomness to. I created multiple timelines with small actions to break up the sequence and wanted to trigger a single one of these timelines every X seconds. The 'single one' part is key here.

Current options:
- Make multiple steps, with each variation timeline becoming a step. I did this in the bathroom interaction I made a while ago. This works for a single set of variations, but changing anything afterwards means redoing the work,
- Use an AnimateProperty event to randomly set the weight of each variation timeline, then make these timelines use the same animation nodes so only the last one in the hierarchy is shown. I used this approach in my last interaction because I wanted multiple sets happening at the same time, so I couldn't split it into steps. This was a PAIN to set up.

Suggestion: Add a way to trigger events (with their own probability check) when a timeline event fails its probability check. I originally suggested it could work by adding an 'else' trigger in addition to 'on start', 'on end' etc. that already exist. I now realize this does not work because these triggers only exist for actions within the event, while the probability check is for the event itself... But I imagine something similar is possible.

Alternatively, this could be extended into more generic if/else logic for events and drivers, allowing variables to be selected (like in drivers) and compared. That would be a much larger change however.