We are a family of four with each of us having a balance of 31,549 miles. These were earn't in Dec06/Jan07 and the balance includes a bonus because of a 10 hour delay in Hnl in Jan.
If your mailing address on the account is in Oz you should have 3 years before your miles expire so no need to rush to add to the accounts with a transaction..
You can check by logging in and going to:
Home > Your Aeroplan > Your Profile
On that page it is listed as: "Account Expiry Date:"
Cheers