Okay for those wondering, after finally getting myself setup, which required my 3rd visit to a TD branch as apparently their web systems are just as poor at AE ... I got the following back from customer care:
Upon review of your profile, I am pleased to confirm that the current Aeroplan credit card account is connected to the following Aeroplan number: xxx xxx xxx.
So, they did apparently manage to take account of my existing number while doing the setup.