I'm trying to figure out if there is a search engine for AA/BA with which I can look at a multi-city routing using different fare classes for outbound and inbound flights.

Example: I'm looking to price out AUS-FRA; CPH-AUS. I'd like to go outbound on economy, but the return (on BA metal) has what appear to be "friendly" fares in WT+ or CW.

If I use BA or AA's website, I can't cherry pick different classes of flights on a multi-city (though I can if I build as "straight" / non multi-city round trip). Matrix gives me the same problem, but at least I can look at how the fare is built on the final screen.

I still can't really build a fare (including the pile of taxes required) this way. The only way I know how is to call the airline directly and get them to price it out for me. So I'm wondering, is there either a sneaky way to do this in one of these search engines, or is there another search engine out there that