Never say never to co-domiciles. In the 1994 CBA one of the first Side Letters, shortly after OAK became a base, was a Side Letter that allowed OAK, SFO, and SJC to be a co-domicile. The side letter even had TFP for ground transportation to get a pilot back to the city where the pairing originated if it terminated in another city (ie. if it originated in OAK but terminated in SJC). For some reason, known only to management, during the entire duration of that CBA (well over 10 years) that side letter was never implemented.