In MDT I was able to constrain 2 models together while constructing them by selecting specific points on the models to form mid planes which allowed me to constrain them together while actual building the parts. Once I had holes or other real features to constrain the model to, I would eliminate the constraints I had temporarily made, and I would simply add the new constraints. Inventor does not appear to do this. I have not had a training class...yet. Do I have to actually build a plane on the part? Also, In MDT I never worried about where I drew my part in space. Someone indicated to me that you need to pay attention while using Inventor. Is this true?