Thanks @Aqua and @ZodiusInfuser for explaining this. I'm still new to all the KSP modding stuff, so sorry for the silly questions Let's summarize your explanation with my less professional words, to be sure I understood everything correctly: - for the movement of the robotic parts a well-defined root-part is necessary, because every movement is relative to that part - when the root part changes (what happens when you dock), then the movement will be wrong, since the direction of movement is done in respect of the old root-part, but there is a new root-part and it should be relative to this now - for mods it seems not to be possible to determine the root part to correct the direction of movement - and mods can also not determine when the root-part is changed, since there is no event triggered for that Best regards, GrafZahl