Thanks for the heads up!! Here the info I found on The CBSA website
Travelling with Children
Parents who share custody of their children should carry copies of the legal custody documents. It is also recommended that they have a letter of authorization from the other custodial parent to take the child on a trip out of the country. Such a letter will confirm that the child is not being abducted or taken against his/her will. The parents’ full name, address and telephone number should be Included in the letter of authorization.
When travelling with a group of vehicles, parents or guardians should arrive at the border in the same vehicle as the children.
Adults who are not parents or guardians should have written permission from the parents or guardians to supervise the children. The permission letter should include addresses and telephone numbers where the parents or guardian can be reached.
CBSA officers watch for missing children, and may ask detailed questions about the children who are travelling with you.