A simple way to make the MDC Human work on Wormwood is a few simple house rules
1.) Food is SDC, period don't make it md don't even think about it.
2.) Only their flesh are md and a punch from one human to Wormwood Native is dealt in MD/SDC. Falling, getting hit with a club and other things will still hurt their internal organs.
3.) Resin weapons are made of MD and deals md due to it's connection to the planet.
I try to keep these rules simple so they are not indepth but quick and simple hope you like, please let me know.