Well guys, after a few weeks of quarantine, I have further developed my theory of how the egg got to Sulaco. It is clear to me that the egg was brought by the Queen of Hadleys Hope.
I think the place where I place it is the weapons room that is in the Sulaco hangar. I know it's not the same as the one that appears in Aliens, but there are a lot of things that were changed in Alien 3, like the shape of the cryo tubes, so I think they are design decisions of the movie itself.
When I place it, I think it's in the time that passes since the dropship docks in the Sulaco, and Ripley Newt and Bishop go down from it to the hangar. I think the queen had time to get out of the dropship's hind leg, lay the egg, and hide again. The rest we already know ...
At the same time I think Bishop is complicit in this situation. I think he knows through the Sulaco's computer that there has been a move by the queen and that she has laid an egg. He is ordered to bring a specimen, even at an internal level of order. So he doesn't warn Ripley that there is an egg. Even in Alien 3, he regrets telling Ripley - That it hurts ...
What do you think?