I haven't tried this and I may be wrong, but I think there is a 3D command out there called "MELD?" which can be used to join 2 solid forms together. In your case a small ellipitical shape to a larger one. Create the 2 seperate solid shapes and then located them in the correct locations, then trim, fillet, chamfer off the pieces you don't need. And then save it as a whole, or maybe a 3D block.or Search a 3D block library for a shape that is similiar or already done for you and modify it to fit your needs ....Hope this gives you some ideas.