Advice please: change of origin of return flight

Is this possible?

Currently booked on a LHR-LAX return in a S.

Plans have evolved and after LA want to visit Oz.

Trying to change return leg to SYD-LHR (will make own way to syd).Family (Wife / daughter) already booked LHR-syd return in G.

Here is where it gets complicated, there is availability of a reward flight in UC, but the flight is sold out in econ/pe. Is anyone aware whether I can purchase/convert a "virtual" L or S immediately into a UC reward where there is seat availability?

Currently VA struggling with this, first time I phoned they were okay, I think, with concept but couldn't see the reward flight availibility. Next time, reward seat availability confirmed, but unable to process a virtual seat.

Otherwise it's obviously travelling via LAX without family.

Grateful for everybody's opinions or whether they have managed similar? ?|

O

Gosh, so you want a return LHR-LAX and SYD-LHR, can you do a return from a different continent on a S fare, that's key (I know you can say anywhere in the US)? Then, you need a S from SYD-LHR to do it, which presumably is where VS is failing to help if there are none available. And even then you need to pay to change.

The simply truth is that if the flight is sold out in S / W (upgradeable PE fares) then your only choice is a one way G from SYD for 100k miles I think? Do you have that many miles?

Unfortunately not enough miles for a one way reward (a bargin 90,000 miles!).