I am sure that our Fellow and former VP Kathy McClurg won't mind if I quote a reply she has received from the CHA to her enquiry about the helmet, and posted on Facebook:
Kathy McClurg OK - I received a response to my inquiry about the helm and further generations from Bruce Patterson, Deputy Chief Herald of Canada, today:
The relevant part to the question of depiction of unusual helm on the grant and the use by descendants:
"In answer to your question, we do not regulate the use of helmets shown with arms; indeed, they are not mentioned in the text of the grant (although sometimes an explanation is given in a symbolism document if the helmet is unusual). Descendants of Ms. Payette would certainly be free to use another type of helmet, and, as the helmet is not a “granted” element, a new grant of arms would not be required. We have never taken the view that only the elements that would be used by the descendants as well as by the grantee should be depicted on a grant of arms; if we did, we would not be able to depict non-granted elements such as honours insignia or granted elements such as supporters."
This is in fact quite logical. Historically a grant of arms could, for example, be given to an Esquire or Gentleman who subsequently becomes a Knight. His family prospers and some years after the demise of the original armiger his heir is granted a peerage. On each occasion the traditional helm, but not the arms, would change without the need for any new grant. The heir would need only to seek a grant of supporters.