Dual CAN/AUS citizen - what passport do I use where?

[shuuy]

Follow-up

. Emailed [email protected] in advance requesting APP link with my flight details, copies of both passports, 72h before departure
. Got a "this is for business use only email response", and nothing further
. Had no issue existing on my CAN passport from Australia at the eGates, or upon boarding

(check-in agent did not appear to have to do an APP link email/call)

Now to see if I get TSA Pre on my US departure using my Australian passport and NEXUS Known Traveller Number...

 

[RooFlyer]

@madrooster o/t sorry, but if I have a USA B1/B2 visa in my previous AU passport, is there any 'linking' process with my current passport that can be done to help things along? I suspect not, but thought I'd ask. I dare say the Americans already have them both in their system.