I was going to start a thread with a related question, having searched unsuccessfully. It's close enough to go here, I think, without counting as thread hijacking -- anyone who can answer your question will probably answer mine in doing so.

Mrs MH and I flew a couple of CO segments yesterday, with luggage. I put my BD number into the reservation to get the *G benefit of checking bags free, intending to change it to my LH number at the lounge for M&M mileage credit. (I've done something similar with UA in the past, soy.)

The CO gate agent and two lounge agents refused to make the change, citing "policy", unless I paid $50 for the bags. Given time pressure at the airport, and the fact that we really need the 2,500 M&M status miles, I paid.

Were the CO agents right? If not, what could I have said to convince them and have I got a chance of getting the $50 back?