Hey guys,

I'm trying to model up a tape cassette and I've made a base part for the common parts of all quarters. Then from this I've made a derived part to model side A. What I was hoping to do was to then put A side into an Assembly file then insert the base part to commence modelling the B side using geometry from Side A. I have no problem inserting the base part but when I try to add to it and make sketches I cannot create relations between the two parts.

Is there a method of being able to do this?