Question for PMM and ImmOfficer

[Suin]

Hello,
Could you please advise me on the following matter. In the country I am from they do not issue passports to children until they are 18 years old. For travelling a kid or kids are always added to their parent/parents passports as well as to another person's passport after both parents give consent for their child travelling with that person.
If the children's entrance visa to Canada is issued into the one of the parents passport (and that parent has full custody for kids), can another person who has kids added to his/her passport enter Canada having that parent's passport with kids' visas in it? The matter is that main applicant is mother and visa is issued into her passport and by serious reason she cannot travel herself, as she is already in Canada, but children must enter Canada before visa expires. Will it work this way if accompanying kids person will have a mother's passport with visa and mother's consent letter on the port of entry in Canada?
Thank you in advance.

[Suin]

I would appreciate your advise very much.