If one person in the family receives AOR everyone receives it... If you have already checked your spam and deleted emails for an e-mail ending with "cic.gc.ca", I would suggest calling IRCC and getting the application number for the missing AOR and verify the e-mail address associated with that application
Since your's is a paper application, you may try logging in to ECAS (link in signature) to find the application number as well. However, you'll still need to contact IRCC via phone to verify the e-mail address associated with that application
Once you get the application number, you can link it with the new tracker (link in signature).