Probably just trigs with the “(NOT)FILL” (with the line over FILL) trig condition. This allows trigs to activate only when FILL is NOT held, thus silencing them (or “soloing” the one track) when FILL is pressed.
You can accomplish this by doing it trig-by-trig, but remember: you can hold multiple trigs as you p-lock the trig condition, so it’s not that tedious.