Colony Recruitment Pref Night
 

From reading the posts here, it sounds to me as though if you're invited to a chapter's preference, then you're definitely on their bid list, though your exact place on it is unknown.

If colony recruitment isn't taking place at the same time as regular recruitment, then the colony must know that all the girls going through recruitment would want a bid from that group and only that group...so they can't possibly lose girls on their bid list to another group. So do colonies only invite girls who are getting bids, barring some extraordinary circumstance, to pref night?

Every sorority conducts its colonization recruitment differently and even those are unique to each campus. The only way to know if you are definitely getting a bid is if you are given one and invited to Bid Day.

As for colonization recruitment outside of formal recruitment, no, the colonizing group will not lose a girl to another chapter via bid matching. There is no other group to match. It may be the case that the girl is not bid or she may decline her bid.