I have booked the same itenary for my family from DFW in march this year on one world by calling in DFW-LHR-BAH-KHI without any hassle( i was about a week flexible).And i have already booked on star alliance in business for next summer DFW-LAX-BKK-KHI. Yes layover in BKK is 7 hrs but i think i can live with it if i am travelling in business.