If I remember it well, it should be:
Y & B as full economy fare, M, U, K, H, L, Q, T, N, R, V.

I never had experience on upgrading from M to O, but in all cases, you will need to have O inventory so that Flying Blue can do the upgrade. For the number of miles, you can ask the phone agent how much it will require to do an M to O upgrade on the whole itinerary as a general question, and they shall be able to check it for you.

Just keep in mind, if you see an opening O on one segment you can still ask to upgrade on that specific flight.