Change the default instrument sound? (E.g. flugelhorn)

Is there a way to specify which instrument voice is chosen for the non GM standard instruments. by default? I've searched the forum, but I haven't found anything relevant.

For example, for both cornet and flugelhorn, the default voice is "trumpet". I get that they're not part of the GM MIDI standard, so there has to be a substitution, but can I choose which voice, instead of it setting it to trumpet?

Personally, the sound I hear in my head when I attempt to play a flugelhorn is nothing like a trumpet. It's closer to a trombone, being played in a high register. For the cornet sounds I want, the tuba is probably closer.

For example, I sometimes import MIDI files with flugelhorn or cornet parts. When I play them, it sounds completely wrong to me, so I usually substitute for the voice, manually, in the mixer panel. It would be nice to set that as the default behaviour. I thought it might be part of the instruments.xml file, but as far as I can see, it isn't.