Canadian Airlines Plus - Using Empress Lounge passes at YVR/LAX

A friend is going to SYD via LAX. She'll be flying AC codeshare (UA metal) YVR-LAX, and then QF LAX-SYD-LAX and CP (AC metal) LAX-YVR.

Will she be able to use the Empress Lounge coupons at YVR? If I read/remember correctly, not ex-YVR. What about on return from LAX?

She is certainly OK at YVR. Both MLL and Empress lounges honour the one-time passess of the other. So your friend can present her Empress lounge pass at the Transborder MLL at YVR.

Ditto on LAX-YVR. Since she is flying on AC metal, she leaves from LAX T2 where there is a real MLL. The Empress lounge pass is perfectly good currency there.