I'm developing and fleshing out this cool scenario. So please, follow me.
Well:
The Return is not the second chapter, or an alternate world, but a sort of spin-off also functioning as fourth chapter. It is set in the future, 20 years after the events of Day of Reckoning.
The "Luc Deveraux" we see in the movie is a clone, like the ones depicted in US:DOR (or even "Andrew" in Regeneration). The main difference is that genetic engineers succeeded into toning down his UniSol DNA component in order to make him stable and useful.
This doesn't ruin the ending of DOR, because the UniSol organization ("The Brotherhood of Chronos") has surely infiltrated state and goverment the best it could, controlling many aspects of U.S.A. and people.
A special project called UniSol 2500 is then established, mainly based on the powerful A.I. known as "S.E.T.H." (Self-Evolving Thought Helix).
On the other hand, Luc Deveraux II is as an half-human, half-UniSol clone, and retains memories of his past life. He conceived a daughter, Hillary, and then started to work as technician and counsuelor for the UniSol 2500 Program, as planned by his creators.
The Brotherhood of Chronos, led by John II (or his successor), watches the program from the shadows, in need to see what S.E.T.H. can accomplish for them.
In the movie, there are no timestamps or dates.