- Solved this with:
Material materialBtgNoMass = materialBtg.DeepClone();
materialBtgNoMass.Concrete.Mass = 0;
materialBtgNoMass.Name = “C35/45NoMass”;
materialBtgNoMass.Guid = Guid.NewGuid();
According to your instructions in link:
https://femdesign.discourse.group/t/custom-concrete-material-solved/394/2
Explanation why I want to used load groups.
I normally use load groups as traffic load on ex a bridge can be placed anywhere on the bridge and it would result in unreasonable amounts of load cases. It would therefore be nice to use the same method for retaining wall but if is considered too much work I will manage with load combinations 
Stopping and importing load groups is also an option.
Have never worked with Github so I feel quite confused 
Have I forked incorrect or should I switch branch?