I promise I have looked at the dashboard and the informative posts around baggage (especially this http://www.flyertalk.com/forum/23593103-post6.html), but conscious that query may not get visibility and answer if posted directly there

Mods - you may want to move there if there's an answer (I didn't want to cross post)

So I have two BA trips booked where I'm contemplating onward flights and through check practicalities come into play

Trip 1: DUB-LHR-SIN-SYD (change of flight number in SIN if relevant, this is all one PNR)

Am seriously thinking of flying to Cook Islands (via AKL) from Sydney, possibly on LAN. Oneworld to Oneworld connection in SYD could be a lot more convenient for me, and can book RAR flights from AKL separately.

I would have a 2.50 gap between flights if operating on time, which is well within the Int'l to Int'l MCT in Sydney (http://www.flyertalk.com/forum/18227269-post2.html) - key issue is: will BA in DUB be able to check bags through on connecting QF / LAN flight from SYD on separate ticket?
(a 9 hour extension to layover with a day in Sydney / QF F lounge is not the end of the world, opting for a flight 1 hour later is A$150 more in Y...)

(I will have window to check bags (or attempt to) in LHR before a positioning flight also, which may be both simpler and more complicated!)

Trip 2: DUB-LHR-HKG (separate PNRs)

Am debating TPE or Kyoto (KIX) on CX as a same day connection in HKG - but may still stop a couple of days in HKG first (Imperial palace opening times a key factor ) - so this would be asking BA check-in in Dublin to check bags through on 3 Oneworld bookings: am I being unrealistic if I even attempt this in DUB?

(Having read this on connecting on 3 different tickets http://www.flyertalk.com/forum/24573519-post87.html it doesn't seem easiest in practice...)

Any wisdom, insights etc. gratefully received!