I've been stalking for a while and have learned a ton from you all, hoping someone can help me with this, or point me to a more appropriate place to ask this question.

Home airport is DTW. I will be in NYC for business May 1-3, flying back to DTW on the afternoon of the 3rd. I had previously already purchased a flight (DL 1405) to MCO the evening of May 3rd, along with redemption of a companion certificate for my wife.

The issue is that one-way direct flights from JFK to DTW are >$500, but is only $190 if I took a flight from JFK to MCO with a layover in DTW, even though the 1st leg of that flight is the same as the more expensive JFK-DTW flight (DL 95). The 2nd leg of that flight is DL 1405, where I already have a seat.

I unfortunately need to check a bag for the trip to NYC. Would it be possible to book the JFK-MCO flight, exit the terminal and check-in with my wife in DTW (allowing the companion certificate to be used), take that flight, and then pick up my bag in MCO (which had been checked through from my NYC flight)? Or will the system not even let me do that because I would essentially have 2 seats on the same flight? Are there any other options that I'm overlooking?

Thank you very much for your help with this.