from what it looks like it would be very complicated to stitch this together in nurbs. you can try to fillet blend them (this will give you smooth blends) and after that - globally stitch it together. going to subd and merge the edged together and go back to nurbs and then globally stitch it together might be an option too. the only thing that will happen, that the individual parts will be differant than what you planned them first to be.