Hello everyone!

I am returning from 7 year hiatus and simply do not recall how I used to do this.
I need to add Instrument Definition for applicable Synths.

Do I need to plug the Synth/Keyboard using USB in order to use Instrument Definition or can I do this with a midi connection?
I prefer to use only a MIDI interface rather than connecting lots of Synths via USB. I can get a 8X8 and just run a single USB connection.
 
I will need to buy a MIDI interface which is why I am asking.

Thanks my friends!

Instrument definitions are not related to connection method at all.

You would need to "find" a suitable instrument definition file (aka .ins file). Sonar cannot create one from your synth. Some instrument files are supplied with Sonar; some can be found on the internet. Of course these are most likely to contain just factory patch names. If you've created your own patches, you'll have to type them in.