All OW airlines have the capability to interline luggage and issue BP for all other OW airlines -- this is one of the conditions of entry into OW (as an aside, it is also the reason that EI left OW -- the cost to change their computer systems to interface with JL was too great). So, the only reason for not having luggage properly tagged and BP issued is a lazy or untrained agent. LA and IB have this problem chronically, but asking for a supervisor invariably results in being able to do it (they know the magic key strokes). You do have to be persistent at times. AY did have a problem with E-tickets until about a year ago, but this is now fixed and no longer an issue. For the OP's journey it should have been done routinely -- shame on LA for having such shoddy agents at their hub!