Ok, just when I thought I was winning....
I can get the 'fresh' workorder looking great:

- WorkOrder Main Page
However, it seems that the underlying logic for allocating input to output cannot cope with this.
In the example presented, the idea is that the *combination* of inputs creates the *combination* of outputs. However, I am unable to (manually at least, I haven't tried programatically) set all the output quantities without getting a complaint about unsufficient inputs for allocation.
I take a look at the allocations page after adding just the first output quantity of 1 for the first line, I see that it has allocated all the inputs to just one output:

- Allocations
And then I get this when I try to set the quantity output value to 6 on the second item:

- Allocation error
- Capture3.PNG (6.99 KiB) Viewed 5255 times
So a couple of questions:
1) can I turn off the automatic allocation so that I can do it manually later? I don't need it happening in real time while the operator is entering the numbers.
2) will that even work? i.e. if I can disable the automatic allocations, and say intercept the 'close' function and do it there, would the structures support it?
3) is there a better way I should be doing this?
4) is this a futile exercise with the 7.2.1 incarnation of WorkOrders? Looking at the (decompiled) code, there are a few places where I can see I'll have to completely override the standard behaviour, with no obvious means.
further to question 2:
In my example, all of the outputs use the 'CUTTING' and 'OVERHEAD' 'parts', and then at least one of the 'J*' parts. Each raw material 'J*' part is a sheet of gasket material, which gets cut with a laser or mechanical cutter (depending on the material). Because not all gaskets are the same size, it is possible to nest small ones inside large ones, and the amount of raw material used for a small one is (usually, but not always, because geometry) less than the raw material used for the big one. And shapes matter too, because different combinations of shapes can produce less waste for a given sheet of raw material.
So there is no single 'primary' output, they are all primary outputs. The overall cost, including waste and fixed costs (setup time for machines), will be divided up between the outputs depending on their theoretical share of the raw material.