Parenthesizing chord names

[Tim McNamara]

A common jazz lead sheet convention is to parenthesize optional  
chords written over the melody staff.  An example is a turnaround at  
the end of a song that is not played the last time through.  For  
example in "Easy Living" the turnaround over the last two bars of the  
second ending is (using the default language conventions):

f2 aes2:7
des2:maj7 c2:7

Rather than writing a separate ending, I'd like to just parenthesize  
the last three chords  over the final two bars so they would render:

F    (    Ab7    Dbmaj7    C7    )

This approach is commonly used in jazz lead sheets rather than  
writing multiple endings within multiple endings or adding codas.   
I've been plowing through the documentation and have searched the  
Web, which has extensive stuff about parenthesizing but nothing that  
I have found to suit the need I have.

Thanks!