@Futurepig
Ha ha. I like.
I'm writing a fanfic thing that (partly) addresses the goings on at Thedus before departure.
I have Ash and Weyland-Yutani actually abduct the original science officer. When he is a no-show at the assigned departure date, Dallas reports him as AWOL and WY assign Ash in his place.
You're welcome to use that if you like (although I will too).
As for the reason why they go so far as to kidnap him, and what the real science officer does afterwards, I'm keeping to myself
TC