At 240,000 points she isn't far off the 289,200 required to fly ADL-DXB-DUB return.
Could other family members transfer points to her to make up the difference?
Otherwise buying 50,000 extra points would cost $1,427.
This sounds like a lot, but might be better value than points plus pay.
I tried booking those flights using points plus pay and I was only getting 0.5 cents per point!
So if you redeemed all 240,000 points you would only receive $1,200 off the fare.
This would leave you paying $5594.49 of the $6794.49 fare I was looking at (1/10/2020-14/11/2010).
However the next problem is availability.
I couldn't find any award seats on QF - so much for all the extra premium seats!
There is fairly good availability on CX or QR and some on EK around those dates.
But those options will cost 318,000 points return.
This would mean buying 80,000 points which would cost $2192
Of course there would be taxes and charges to pay as well.
This compares to the cheapest Y fare which is $1336 but that is on EK and not upgradeable.
The cheapest upgradeable fare on QF metal would be $2127.
And that could not be upgraded on the segments between London and Dublin.
If you could upgrade all the other sectors it would cost you 277,900 points anyway!
So you'd still need to buy 40,000 top up points for $1155.
And you would need to seek upgrades for 5 sectors.
I don't fancy your chances of succcess on all of them, and you won't know until the day before each flight!
In summary of the above.
(1) Buy 80,000 points and book business reward flights on CX/QR/EK metal - $2192 + 240,000 points plus taxes and charges = certainty of J for all sectors.
(2) Buy 40,000 points, book economy cash flights on QF metal and upgrade - $2127 + $1155 = $3282 + 240,000 points = upgrade lottery, LHR<->DUB in economy.
(3) Use points plus pay to book business class flights - $5594.49 + 240,000 points = certainty of J bookings all the way but what a waste of points!
As you may guess I would favour option (1). It is clearly the cheapest and gives you certainty she will be in J class all the way.
Also note option (2) would not allow a stopover in Dubai.
Although I think that is overrated.