no-body assembly... scaling

Hello, we are trying to scale a tree model we got from a guy who modeled it as a SW assembly, you can see it in the below image...


It is graphically quite okay but we would need to shrink it...with a scaling factor of 0.4

We tried to use the Part Copy from an assembly which works quite ok with SE models but we see that there is no "valid body" inside this asm.

We assume that we would need to spend time to re-create solids with all the entities but it is too long.
Is there any other way than "part copy" to scale something in SE ?