When the chance effect exercises the null option (i.e. the positive choice did not occur) does it effectively blow away the entire chain of effects and the original note on event?
Or does it blow away only the preceding effect (or note on event if there are no other effects)?
The second way of working would be vastly, vastly preferable I think. If that is not the case then maybe an “Otherwise” effect could be developed so that a branch to another effect would happen in the null case.