I'd like to clarify a myth with regard to transfers to mainline from baby. You currently keep your group date of joining but you join the seniority list at the bottom. This means that you are protected in the event of redundancy consultations as your previous time served counts for you. However you don't get any preferrential bidding rights over those that have been there longer.
Given that this doesn't appear to be reciprocated by baby any more, I imagine that any new transferees will shortly lose that right, which would be a shame for them as it might make them think twice about moving. However, I can't see the mainline CC, who seem a deal more capable than baby's, reacting any other way.
AFAIK regional and mainline maintain this mutually beneficial stance, and anyone moving to regional in this latest recruitment would expect the same.
Max