A polychord occurs when two different chords are played at the same time. For example, A Bb major 7th chord and an Eb chord. It is typically indicated as a fraction:
In order to stack chord symbol text as a fraction in Sibelius:
- Enter the chords in the normal manner, but just include the root of the bottom chord. In this case: Bb/Eb
- Select the bars you want to change and choose:
Text > Plug-ins > Chord Symbols > Chords Symbols as Fractions.
- Go back and edit the suffixes as needed. In this case, add Ebmaj7.