Advice please - UC G, J and Z tickets

Would value a bit of advice please.
In Oct/Nov we're taking my Mum to NY and Washington for her 80th b'day. A couple of months ago I managed to get 4 Gs out to EWR and back from IAD - I was pretty happy to bag 4 in one go.

I left it til later on in the year (now!) to book myself a flight, hoping a G would come up or a sale would appear, (like BA yesterday).

Unfortunately the cash price for that trip in UC is £4800! There's one G available return but nothing to EWR and expert flyer shows only 9 seats left in the cabin all J and no Z.

So, what should I do?
1. Book an upgradeable PE ticket, take the G back and wait to see if one outward becomes available.
2. Book a single G back and wait to see if a G out becomes available (risky)
3. Wait to see if a UC sale happens soon and get one for about £1.8k (?)

I'm obviously not flexible because we want to travel out together.
Also which PE fares are upgradable and do I have to book over the phone?

Many thanks for the advice, much appreciated.

One option I would look at to reduce the cost - if is was for you alone - is an ex-EU (which includes Inverness and Edinburgh) which whilst involved extra flights for you might be a way of getting you onto the same flights as the rest of the family. VS recently had some good ex-EDI deals.

You can book ex-EUs on VS using expedia as the VS site is rather limited (AKA totally useless)

Another to look at is are there any G's from LHR to JFK and IAD-LHR. You won't be on the same flights to NYC but you'd be in the same city!

Expert flyer only shows a maximum of 9 in each fare bucket (which may be duplicated for a cabin) regardless of how many there are so there may be more.

As you can't combine one way revenue with one way reward anymore I would book a H out and the cheapest economy classic flight back and then upgrade the return to the G with miles.

Keep an eye out (several times a day) for a G becoming available for the way out and grab it if it appears. If not and the are still UC seats available on the day (but not G) get to the airport early and upgrade with your miles there. If both of those fail you'll have your PE seat to fall back on.

Upgrades not available from K class PE to Upper.
I have always booked by phone after checking on line. Sometimes checked 5 times a day!
I'd get upgradable PE and keep trying.
I wouldn't book one way it works out more expensive even for reward flights.

Dick D