Thank you @Chris Seveney and @Wayne Brooks for the quick replies.
The investor that approached me used the term "deed in lieu" and "subject to" and I was under the impression that the "deed in lieu" was the mechanics of deed transfer to accomplish a "subject to". I think my understanding is incorrect on this.
I've had other conversations with the potential buyer and they seemed to clarify that their proposition is a "subject to" and are proposing a "wrap around mortgage" to help secure up the payment default risk which seems to take some risk off the table from a Seller standpoint. Even with a "wrap around mortgage", there is still Due on Sale risk, from my original mortgage holder. However, I would imagine that Banks will become more active in this realm of calling in loans upon seeing any activity of a deed transfer in order to bring their yields back up to much better rates.
The proposed sale structure was to pay cash for my current equity and sell the property "subject to" or "wrap around mortgage" the 1st lien. My question is still, would this structure allow for a 1031 exchange for me (seller)? My limited understanding is that it would not, based on the concept of the debt carryforward concept of the 1031 exchange rules. Meaning, how can the IRS track my existing debt on my sold property, whereby I need to have that same amount of debt or more, on the upsized new property that I would buy within the 1031 time frame?