Sometimes a specific chord postion sounds better than the one you would normally use by default, but you forgot the fingering postion required. Or maybe you just don't know how a specific chord is played.
The option of adding as little as one - or as many as needed - chord boxes to any given chord would be a good idea.
Fitting it in without shrinking the the whole page such as when you choose the guitar chords option would be difficult I assume. I use an Ipad Mini and if the sheet was any smaller, I'd have to start squinting and riding my face on the Ipad? Lol.
Another idea is adding some way of adding single note lines. This one is even more important.
Maybe a chord box shape that you can input dots or numbers (tab)?!