Conflicting answers: Individual RESP Account with two Subscribers (Co-owners)?

Context, yes, the chat bot claims only a family RESP can have co-owners, which I am taking to mean Subscribers in the language of Canada's RESP rules. However, I have seen others claim (I think) they have co-owners for an individual account. Can anyone confirm if that is true?

Also, is there any downside to having a family plan over an individual (if there is only a single child in the family)?