I think you probably need to get proper legal advice. The issue is whether your daughter would be viewed as a sub-tenant of her friend, or a tenant of the landlord. If she's a sub-tenant, then she's paid her rent, and that's the end of it.
It might be worth telling the landlord that the correct avenue for him to follow is PRTB, and that any further correspondence will be ignored unless they follow corrrect process.
It might be worth telling the landlord that the correct avenue for him to follow is PRTB, and that any further correspondence will be ignored unless they follow corrrect process.