My wife and daughter fly out tonight on SAS, ORD to CPH in business class. It is the first leg of a "trip of a lifetime" around the world. Yesterday SAS did a plane swap for the flight from a A330 to an A340. (thankfully not to LN-RKP). I know this happens and not a big deal. The odd thing was that although the first eight rows of business class are laid out identical in both planes (A340 even has a couple more rows) they switch their two blocked seats. In the grand scheme of life this is a minor annoyance but it is a little frustrating that we had bulkhead seats blocked for them since last June on this flight. I called SAS and of course can not move them now that everyone is reassigned and got the "they were never guaranteed". My question is why not just move seat assignments identical for all from A330 to A340 when the plane changed?