In addition to Trev's thought here are other possibilities that you might also like to investigate.
If you go into Realtrack picker, some Realtracks (not all of them) have a 'Held' option that can be activated (see the image below)
If you want a single track with Realtrack held chords, try...
- enter Realtrack picker
- select the held option
- exit Realtrack picker
- mute all tracks except the one you want
- regenerate the song for the changes to be implemented
There are also a few Realtrack instruments that are 'held' as well. If you type 'held' into the filter within Realtackpicker (no inverted commas), you will find them.
For MIDI styles...
There are three midi styles with held chords. These are
1. pianohld.STY
2. Sw44Held.STY
3. HeldBosa.STY
Regards,
Noel