Bogus, I believe Prometheus occurs in the same solar system as Alien/Aliens, but that its NOT the same planet/moon. However...I believe that around the Middle Ages, a Engineer bomber took off from LV223 (Prometheus planet), already infected its engineer, who got sick, and made an emergency landing on LV426 (Alien Aliens), but died. And there were no engineers awake and alive (one sleeping the rest dead) to come to rescue or recover him.
Now...Nostromo may have been directed by updates to its FMC to investigate the "distress beacon", perhaps in hopes of finding out what happened to Waylands' ship?
And semi-officially, the Predator race exists in this universe....were they created by Engineers too? Are they the "expendable drone workers" of the engineers?
Were the Aliens the atom bomb, able to reproduce at an exponential rate and then wipe out life in that region? and Predators the SpecOps SEALs and CIA operators who could do covert close surveillance and assasinations? And not know it conciously but solely thinking in terms of lust for the hunt, the challenge?