I was thinking about trying this on an upcoming trip. I'm flying Delta-coded and -ticketed DTW-CVG-IAD-CDG-FLR, FCO-CDG-IAD-CVG-DTW, operated by a combination of Delta, Comair, Air France, and CityJet. I have paper tickets.

For the last leg, should I be able to fly NW non-stop IAD-DTW to avoid the layover in CVG?

(In case you're wondering, I chose the routing a. to be able to fly with my S.O. who lives in D.C., and b. because it was ~$350 cheaper than NW/KL DTW-AMS-X for the same dates and cities.)