Thx. Given PE prices are roughly about business class with MH (via pay+points option), wouldn't this be better?? I'm a QF bronze member so not holding out for any success with upgrade..
Sounds like you have answered your own question - $5200 on QF Y+ or $3900 for MH J class is a fairly easy decision to make. Short term - your suggestion of using enrich and points + pay for the second ticket may be the best you can do anyway and may still be better than paying full cash price for J class fares. As others have said - unless you can somehow collect all those points in dispirate FF programs and Credit Card programs into a sizeable amount in one program you will struggle to be able to redeem, especially at short notice. Splitting up the big problem into 2 smaller manageable problems of Oz to Asia and then Asia to Europe may increase the complexity but get you better value.
I would just sanity check all the Y+ and J class points + pay options and fully paid fares in a big list all the way from "backpacker horror" 30+hour trips to Europe on 3 different airlines in Y class ($1200 UAD) all the way through to fully paid First Class tickets on quality carriers such as EK QF SQ etc (say $12K AUD?) and then start eliminating stuff you cant accept on the cheap end and eliminate the stuff you can't justify on the top end. Thats a process I always go through whenever booking any flight or redeeming a lot of points with my own money/points.
There are lots of opinions about earning to one FF program rather than spreading yourself too widely among different points schemes but in the future it will be worth considering which FF program you may want to concentrate on (i.e. Oneworld QF CX MH or say *A SQ and its loose affiliations with VA NZ and EY.
In the future you will need to think about where all your FF points come from, where you are currently flying in Australia (VA or QF or both?) and worldwide, and if work pays for any flying then how much status credits do you earn/get for free? Would you like to get enough status to get lounge access or will you get it anyway from flying J class? Are you prepared to do SC runs, or not? what Credit Cards you use or are prepared to swap to, what exchange rate or conversion rate you have to deal with from say Amex points to other FF programs, and obviously family pooling may come into it to pool points and Status Credit into either yourself or your wife. Don't forget that warehousing points in Amex MR points is a legitimate technique to keep your options open if you are not exactly sure of where and with which airline you are redeeming with, as long as those options remain open and are not devalued too much. Don't let tonnes of points expire if you can help it - I say better to get a less optimal/coughpy redemption than having them expire on you!
Don't forget to consult aforementioned wife about which direction you decide to go!

She may have to adapt her spending patterns and travel patterns to align with yours. If you can get good enough status and accumulate enough points in one FF program and get that to a level where you feel like you are getting some value out of it (even if its just an annual upgrade domestic flight from Y to J class) then you can explore status matching and getting value out of more than one FF scheme.
Everyone is different and I can't control whom I fly with (BFOD policy) so I have to keep a foot in each camp (QF and VA), but even with my modest flying and lifestyle I have found some great tips from members here about how to maximize my own $$ spend and own use of points to maintain status. Who knows - maybe you can control who you fly with - in which case I am sure there will be much better experts than I on here who will make their own better suggestions.