Thanks everyone for your valuable advice. So my sister is finally in the middle of her DONE4 trip! The itinerary was slightly changed because of avilability, etc. as follows:

BOM QF X/SYD QF MEL QF SYD QF OOL //BNE QF PER BA X/SIN BA LON BA MCT BA LON BA NYC AA SFO CX HKG CX BOM

I managed to get it validated by AA and had it issued in India. BA, CX or QF were not willing to issue it!

Now, I have 2 questions:

1. I am unable to get a seat from SIN-LHR on 1st December on BA or QF or via HKG or BKK on any of the OneWorld Carriers in D class. Is there any other routing that can be used to get from PER to LHR without violating the DONE4 rules or using up one of the two UK to Middle East segments.

2. For purposes of the two segment restriction between the UK and Middle East, can you do get between the Middle East and London on a OW cooneecting flight that would not violate this rule?