I will probably defer to my colleagues so they may provide you with additional detail.
First of all a third party would be, to my understanding, an entity with whom there is a contractual agreement. For instance, the federal government signed a contract with tenants, signatories of an agreement. In the current situation, some stakeholders are not third parties. For instance, Tourism B.C. is not, because it does not receive funding from the federal government; there is no agreement. The multi-party agreement does not apply. It is a provincial agency funded through hotel tax revenues. So, we can bring pressure to bear on this agency, inspire it or discuss the importance of official languages. I have indeed had this type of conversation. However, it is not a third party, technically speaking.
Is my definition of a third party correct?