I'm not sure of some of the rules regarding earning miles on partners and wonder if anybody could explain the rules. I'm giving some examples of situations I've experienced.

1) I booked a flight using Air China flight #, operated by Shanghai Airlines. I requested mileage credit and received a response saying the operating carrier wasn't a partner. That was clearly not true, so I was able to get credit after writing back.

2) I booked a flight using Cathay Pacific flight #, operated by Air China. I requested mileage credit and received a response saying I can't get mileage because of the codeshare flight #. Is this correct?

I always thought that the only thing that mattered was the operating carrier. Now it seems that if one books using a codeshare flight #, both the codeshare carrier and the operating carrier has to be partners of UA. Is this policy spelled out anywhere?