Sorry, this is the correct attachment.

One option would be to put the optional notes in an unused layer and resize the notes using the [Resize Tool].

(BTW, what do those brackets above and below notes mean. I'm not familiar with harp/string notation)

The other option would be to use the ossia workaround. (I'm on Windows, sorry)

Step 1:

Add two staves to the score using the [Staff Tool>New Blank Staves]. Decide if you want them above or below the original [Staff Tool>Reorder Staves].

Step 2:

Define the staff group so that barlines go through staves. Using the [Staff Tool], right-click on the handle that appears on the clef of the staff you want to define. Select [Add Group and Bracket]. In the Dialog Box, make sure [All measures] is selected (located at the top), define the range for the top staff and bottom staff, ensure that barlines are drawn [through staves].

Step 3:

Enter the music for the optional parts in the measures you want.

Step 4:

Select the complete range of your optional grand staff and hide the staves from the score, [Staff Tool>Hide Empty Staves]

Step 5:

Using the staff style [13. Force Hide Staff (Collapse)], hide the measures surrounding the optional ending. [Staff Tool>Right-click>Select Appropriate Staff Style]

Step 6:

Aesthetics. Add a brace (if desired) using the expression shape creator, and a complete left barline (should already be created in the [Miscellaneous] expressions as a vertical line). You can adjust the length of the vertical line by double clicking it and dragging the bottom handle down, so that it meets the left barline of the original staves. Also, you can decide if you want staff size of the ossia to be full-size or reduced (70-75%) using the [Resize Tool].

If this is at the end of the piece, why not just treat it as a coda measure, with text to explain that either option A or B can be used?

Or, working off what George suggested, enter a blank measure, and hide it with a staff style.

I either case, it would be less confusing than trying to put all the notes in a single measure. Just change the ending barlines as needed.

That's perfect.  How do I change the ending barline in measure 30?  This is what I have right now.

With the selection tool, right-click in that measure. From the context menu, select Barline > Final.

Terrific, never knew that.  Thanks!

Also George, the brackets above and below the notes indicate finger placings.  Thanks for your help!

Ok. Sounds like it's pretty specific. Glad you were able to find a solution that works for you.

I've often contemplated writing something for harp but I know nothing about the harp ... and it's a bit intimidating.