Originally Posted by
MrPink
I think you can safely expect baggage allowances and priority boarding when it comes to US and UA. Beyond that, you probably won't get much. I definitely wouldn't expect upgrades or priority seating - UA and US don't extend that to each other's elites. UA doesn't even offer E+ to *A elites anymore.
CO silver is *A Silver in UA's eyes. I agree with MrPink. I do think you will get 100%EQM/RDM on UA paid fare. But however, not sure if you will get 100% EQM/RDM on other *A carrier such as SAS/LH/LO.
For Bonus RDM, for UA and current policy, only UA and US metals will give you double RDM with some exception flight routes (such as Lufthansa metal TATL will also give you bonus RDM). However, but for all other *A flights, I don't think you get bonus RDM. I had flown SQ/TP/SK/TP/TK with other *A carriers, I had not gotten any bonus RDM.
I think if you go to UA website and look up UA's airline partner EQM/RDM policy, CO will more and less mirror UA's *A policy.