MFU on part of an itinerary?

[pilot]

I had a quick look for a thread on this but couldn't see anything so here goes. I'm looking at a trip back to Oz from London plus a bunch of internal flights in Jan next year and want to upgrade some flights with points but not all of them.

Specifically I am looking at flying on QF10 LHR-SIN and QF52 from SIN-BNE. I want to upgrade the QF52 flight but not QF10.

Similarly on the way back from PER-LHR I would be doing QF71 PER-SIN and then QF9 from SIN-LHR where I want to upgrade QF9 but not QF71.

Is it possible to do this?

Additionally, do either of these flights (QF52 and QF9) have Premium Economy or is it only Business?

Thanks in advance!