I am being told by 3 agents with different levels of confidence that, in case of schedule changes, they cannot re-book you on anything other than DL, KL and AF, even if award space exists on the partner airline (RO in my case). Has anyone else heard the same?
Edit to add: the last agent was able to add the RO flight to my itinerary and I saw that on dl.com, but was unable to proceed further, which makes me think that what I am asking is really not possible. But what if you go somewhere in Asia where there is no DL, KL or AF?