(apologies for the late reply, but this is a common question - I'll port it over to GitHub discussions etc. as part of building up OpenSim Creator's FAQ/support platform, which I haven't established yet :(). The mesh importer automatically adds offset frames between each mesh and its associated body...

Hi Soh, Although this doesn't answer your question directly (in terms of overriding `getExcitation` specifically), one thing you can try is to override `OpenSim::ScalarActuator::getControl` instead: Source: https://github.com/opensim-org/opensim-core/blob/master/OpenSim/Simulation/Model/Actuator.h#L...

Another thing you could try is OpenSim Creator, which includes basic support for deleting things from a model: https://github.com/ComputationalBiomechanicsLab/opensim-creator The support for it is super basic. It will probably encounter an issue deleting a body that other components are (indirectly)...

I've managed to convert the file for Maud into an OpenSim4 file by opening it in OpenSim4.0 (not 4.1) and re-saving it. The resulting file can then be used in OpenSim4.0 and OpenSim4.1.