I called today to book two tickets for my father and I in J from LXR-DOH-TXL. After initially being told QR was not in OneWorld, the agent found both legs and went to ticket them...only to have her come back saying the rate desk couldn't figure out the taxes and they'd call me "within 72" hours.

I'm not sure if a simpler routing on QR would have produced an immediate booking, but it seems possible via telephone.

I'll report back if the rate desk ever gets back to me...