BWIA is beginning to codeshare with UA, hence the start of services to IAD (Dulles) as its first US expansion destination. The UA deal is the one being bandied about as UA is keen to extend its reach in the region. I do not know if a deal with CO is in the works but it seems rather unlikely, seeing that they have been partners for so long but with little more involvement than the shared frequent flyer programmes.
DL codeshares with Air Jamaica on flights to KIN, MBJ and also BGI and UVF from JFK; DL itself flies from ATL to MBJ. A codeshare with BW therefore is seemingly out of the question, especially since BW and JM do not themselves collaborate. (In fact, the short-lived JM service into POS was supposed to feature a DL codeshare with respect to service from JFK; the 5-times weekly JFK-BGI flight would have connected with the daily KIN-BGI-POS service to give Trini passengers the opportunity to fly JM/DL to the USA.)
Hop to it, fly for life!