Can I get a friend into the lounge if they are on a BMI code share but AC metal? (I'm elite and I'm on the AC flight)

In YYZ they would be boarding AC metal (bought through BMI) and then transferring to BMI metal in LHR.

Could I get them into the YYZ departures lounge?
Could I get them into the LHR arrivals lounge?
Could they even get into the arrivals lounge? I know that they would have to clear customs and get out - but they have a 10 hour layover at the airport - anyone done this? I think their bags would be checked through - would that be an issue?

thanks