That's the part I just posted. This is the master body and its impossible to downscale it by changing its parameters.
I'm gonna contact our company's autodesk support tomorrow, so maybe we'll find solution together. I'll let you know.
Ok, only possible solution it to make all sketches, planes and geometry (you need to derive) visible and shared in the main tree. Then you can select them when using derive function. I hope it will work