Solo instruments from groups of instruments

Is it possible to load two sound samples for the same stave and have some text (like "solo") trigger the switch to a solo player? Like in the Violas section, if I wanted a solo violist, I would just write solo and it would play a solo viola.

Edit: this is for finale

you should be able to create an expression that will change the instrument, like with pizz. and arco.

I may be wrong, but I'd try a "patch change" with your solo expression, which would upload the new solo sample.

If you're using Finale GPO (or Full GPO or any NI VST plug-in), you could set it up in the Kontakt Player. You'd load two instruments and assign them to the same channel. You'd then load a third instrument (possibly just one of the first two again) and assign it to a different channel.

Then on the staff you would use expressions that have their playback definitions set to channel changes. When you want 2 people playing, you set it to the channel that you loaded the two people on. When you want one, you set it to the other channel. You have 64 channels to work with, so you should have enough.