Pictorial cancellation contact?

Hello! Does anyone know how new pictorial cancellations are proposed? Is it through the same committee as stamp designs themselves, or because of the more limited reach, an internal process?

A landmark, publicly-owned local building (which once served as the local post office) is having an anniversary later this year, which got me wondering about the process by which post offices get this sort of cancellation. I’ve tried asking Canada Post itself online, and they misunderstand and think I’m proposing a stamp design, or alternately, don’t reply.

Thanks!