Hi guys,
This is on the "wish list" but honestly this is only the second time that I can ever recall that this has been asked for, which unfortunately doesn't give it a very high priority for getting done soon.
David's suggestion of having a hidden "performance" track is a good one. You could do that, with the as-performed notes on that staff. On the "score" staff you would have the correctly-notated note, above which you could use Text/Free Text and then use the Mixed Text feature to add the ornament symbol over the note.
Doing this would allow you to have the correct notation for print-out, while having the proper performance of the ornament.
Sorry for the inconvenience, but there is a way
ttfn,
Sherry