I was flying to Manchester, United Kingdom last year on Delta. My flight from BOS --> JFK was cancelled and I was rebooked on UA. Because it was a later flight, I missed my JFK --> MAN flight and was rerouted on SN through Brussels. Although the extra stop was an inconvenience, it did result in me getting enough extra miles to move up to the next elite level! I received miles on DL for all three segments - including the UA operated segment.