Different Instrument for One Staff/Track

Dorico 4.3.20 on Windows 11

I am using VSL Synchron Special Editions for playback (thanks to the excellent help here).

Is it possible (without too much complication) to assign one staff to a different VST/virtual instrument?

Example: VSL plays the orchestra and Synthogy Ivory or Joshua Bell plays the soloist’s part.

Thank you. --Konrad

Of course.
Load the new VST in one tab of Play mode (VST & MIDI) and then assign the sound from that VST in the other tab of Play mode (Track Inspector) for that instrument.