Really? Damn, I don't remember this. I didn't reread Foster's AlienS since maybe two decades, though... Since it's my less favorite Alien movie by far, this book collects dust somewhere in the depths of my shelves.
It's always great to see what parts of the early drafts are used in his novelizations. In his Alien, the eggmorphing scene appears, although it doesn't evoke the eggmorphing process, but only clearly establishes Dallas was impregnated.
I didn't read the Alien: Covenant novelization yet (only Origins), but I hope some early elements once again make it.