Since you are the adult, you are going to be the person who would be declaring.
On the Yes/No box, it's clearly written: Currency and/or monetary instruments totaling CAN$10,000 or more. If you are carrying CAN$12,000 (including foreign currencies), you must tick "yes".
Even declaring is no big deal. Just complete another form after given instructions from a CBSA officer and you are well to proceed to exit. If you don't want any hassle, why don't you wire the money?