Originally Posted by MSPeconomist

DM phone agents have told me that DL would rebook me in such cases.

However, assuming that you can fly on the same day, at worst you'd be eligible for SDC/SDS if space is available, while if there isn't space, you cannot be rebooked.

I assume that these are one way tickets, with the domestic segment after the international flight, right? RTs or changes to an partner ticket would be more complicated.

However, I'd be concerned about whether DL can see your DL operated flight since it used VS miles and presumably VS ticket stock, perhaps VS codeshare flight numbers too. Have you tried to "link" the itineraries?