I know someone has posted about tis recently but I can't find the thread.

Trying to search LON-AVL with the thought of using BA, however there's a glitch in that I get the "Sorry, we have no flights available" when searching, even though one could fly LON-XXX-AVL , with XXX being one of about 5 or 4 options in the US, then continuing with AA.

I know I can manually put in the various stops, but that's a tedious way to search for just the simplest/cheapest option each way, on the one PNR.

What's the best way to search this?