Just now I’ve found HOLD and RELATCH modes to useful for this.
While in LIVE mode press 2nd + Play/Pause. The icon at the top right changes to H or R.
Hold mode is awesome for creating arps that repeat indefinitely even if the patten restarts. No Trig >1 mode required. You can then easily add or remove notes from any octave to the arp.
Relatch mode is similar except all notes are cleared when you key in ANY notes.
Hold some notes, add an arp, automate a chance line, maybe the swing, or other fx and you could easily generate a self sustaining, self similar, non repeating melody.
I’m haven’t yet tried to see if it’s saved with the pattern.