Originally Posted by RealHJ

For non-DL flights DL claims that they are absolved of any responsibility for reaccommodating you. If the non-DL schedule change or cancellation breaks your travel plans, then all that DL will offer is to cancel your ticket and refund or change to alternate available award flights (if any). So, if there are no open award flights, you are out of luck: all that DL will offer you is to cancel and a refund. Now, if you contact the operating airline, you may be able to get them to open up alternate award flight availability for you, but if they are reaccommodating their pax on non-SkyTeam flights (e.g. only flight on a route is cancelled), then you are out of luck, as then no matter what, DL can't book it under award fare classes for SkyTeam and DL partner airlines - which is all what DL will do. In short, cancel for refund or change to alternate available award flights - that's it.