hey jas, you may want to try a trick i use to speed up developement of near identical controller groups ie; replicate entire voice parameters of voice1, voice2, voice3, voice4…. in your case, upper – lower.
use wordpad to open the .panel file to rename the sysex with the byte that distinguishes each voice. do this by selecting and renaming each section of voice code one by one… speeds it up for me anyway