Decades ago, Opcodes "Studio Vision"had a feature where you could combine multiple midi outputs (Today that would include multiple VST instruments) and save that as an instrument.
Saved would be the note range of each instrument and/or output, velocity switch or crossfade, keyboard mapping that could also taper the velocities so that the range of any instrument would taper instead of hard note limit.
Theses you could save and recall into any new project.