Upgrading an Award Ticket Booked via Aeroplan
 

Apologies in advance if there's a thread this belongs to, but searching didn't turn up anything too relevant.

I booked LAX-HKG via an AirCanada Aeroplan redemption (eco, X fare), but would like to possibly pay for an upgrade to Premium Plus or Polaris.
The United site and online chat can't do this... are there any good options? Unfortunately I don't have enough UA miles for two of us, otherwise I'd probably have done that...

There might be an upgrade offer during check in.

You can change the Aeroplan award if I saver award space opens up, there may be a fee etc. Also Aeroplan seems to block premium direct space on partners, but you can add a throwaway segment.

Does it show the 'upgrade' button on the website or app? It usually works for partner award tickets. At OLCI is another chance to snag one - T-24