from the manual:
“If you set an instrument definition with a channel number = 0 (instead of 1 to 16), every “not defined” instruments of the selected output will be defined as this definition.”
So if you plug the Blofeld into midi B, then you only need to have one def file on channel 0, set to midi B and you’re good to go for all 16 channels of the blofeld. Too bad the blofeld can’t really perform with 16 parts. I usually do about 3 or 4.