1) Will Delta allow you to volunteer if you have downline segment on another partner airline such as Westjet? I am flying ATL-YYZ-YHZ next week (YYZ -YHZ is DL7060 operated by Westjet) and ATL-YYZ has been frequently offering VBC's lately. Would they see the WS (DL codeshare flight number) and decline?
2) If your downline connection was long enough that the next flight they protect you on, you would still connect to your original final segment, would they offer you the deal? In my experience, I doubt that the agent has time to inspect your PNR with that much detail to even know that until after the plane is gone...