I just had an idea:
Make it a dream. If you plan to set it between 'Alien 3' and 'Alien: Resurrection', make sure it is a dream. That doesn't contradict anything, plus it will exempt the film from any criticism in terms of differences and new things added contradicting. Any difference in the Alien's abilities can simply be explained by the fact that it's a dream. Though please don't edit the Aliens abilities.
And please don't ruin the mystery of the Aliens. No showing them grow or something like that. Mystery is good. Modern filmmakers don't seem to understand that but it would be great if they could.