Thank you, although I don't think that's always the case. I was booked MEL - DXB - ATH - LHR. This was QF - EK - BA, with first to ATH then on a separate ticket I was BA from ATH - LHR in economy. No issue with a 30kg bag checked all the way through. To be honest, I was amazed it was done given the mix of airlines and was prepared to pay excess, however it worked fine. Was electing something similar for the above, albeit BA the entire way.