Not sure best place to ask this but have been going round in circles for a week!

One world 'tool' says OSL-xLHR-CPT-xDOH-DFW etc is valid routing.

So question is OSL-xDOH-CPT-xLHR-DFW....also valid routing?

And which is likely to be the cheapest in terms of tax/surcharge addons

Bring forward my RTW booking to use BA upgrade voucher before they up the prices on the 27th to use to split the rtw over two years