Yes, you will earn EQMs on another *A carrier and it doesn't matter whether UA flies there. When I fly to a European destination, I almost always fly LH onward from FRA or MUC and always get EQMs--well, almost always. If the LH flight is a codeshare operated by a non-*A carrier (as happened to me this summer on the way to Belgrade), no EQMs will accrue (check to see who operates the flight). Also, different carriers offer different levels of miles (including EQMs) based upon fares. This past spring I flew SAS from Copenhagen to IAD and got only 25% of the actual miles, either as redeemables or EQMs, because my fare was deemed to low. So check with the airline before you buy. A higher fare class is likely to get you the full mileage quotient.