Remove part from part

Hi all, I am trying to remove a part from a part, while keeping the part to be removed, or to get a similar result.
I have two parts. The one to be removed(a cutting blade) that needs to remain untouched. The second part, on the other hand, is a plastic piece. Basically, the blade goes into the plastic part, so in the latter I need a recess of the same geometry as the blade. Of course I would like to keep a connection to the original blade part so that if I make changes on that one they are also reflected in the cutout. I can copy the blade body to the plastic part so I can use the Boolean removal function, but then I don't know how to accurately position the blade body relative to the body of the plastic one.
Any pointers on how to proceed? Thanks