The relevant Canadian regulations reads:
Subject to subsection (2), no person shall act as a flight crew member or exercise the privileges of a flight crew permit, licence or rating unless
(amended 2010/02/02; previous version
the person holds the appropriate permit, licence or rating;
The "privilege" would be primarily to act as the pilot in command. A Pilot in Command is responsible for the flight as a whole. A "flight Crew Member" would be a person who is entitled to exercise the privilege, and is required for the flight in terms of minimum required crew for that aircraft.
Therefore, for most of our GA aircraft, there can only be one flight crew member, unless it is a training flight, and that one flight crew member would have to be the PIC, so would have to have the appropriate license.
That said, I don't see anywhere in there where there is a prohibition of a non flight crew member handling the controls. Elsewhere it says that you have to be an instructor to provide training, and nothing says "go ahead and let the passenger fly for fun", but it is not prohibited either.
If a PIC is not satisfied that they can safely conduct the flight with a non pilot handling the controls, that is entirely up to them, and that is to be respected. However, in the absence of a prohibition, and if the PIC is comfortable letting another person to fly, I cannot see how it breaks a [Canadian] regulation.
Transport Canada had at me once, when an inspector became aware that on a weekly basis I rode around right seat, while the owner, who had lost his medical for a year, flew his 182RG around. TC tried to convince me that my doing so contravened regulation - but I did not see how. I was the PIC, the aircraft did not state which seat I was to occupy, so I acted at all times to assure that the flight was conducted safely - I just did not fly it myself.
There was chatter about the risks of pilot incapacitation, or loss of consciousness, and that I had to be an instructor to allow him to fly. Why, I asked, do instructors have incapacitation training? Not usually!. I could be left seat, and my non flying passenger become incapacitated, with every bit the same risks to the safety of the flight as though they'd been flying on the left when it happened. There seemed no retort to that logic.
Though TC was not going to condone my letting him fly, they seemed to decline making an issue out of it either....
If you are truly comfortable, let another person share the joy we do! I try
to get every passenger to fly a bit if they will....