Waiting for My Appointment Letter: Is My Offer from a Sister Concern Still Valid?

I received my offer letter from a sister concern. Now, it's been two months, and I have not yet received any formal appointment letter from the main concern.

I received my offer letter from a sister concern. Now it's been two months, and I have not received any formal appointment letter from the actual concern. Some employers play smart by showcasing a big opportunity but confining you to a limited space with no room for development. If you are brave enough, ask your employer about the status of your appointment. Ensure you have clarity on the situation before deciding your next steps.

Regards

Thank you, actually, I was referred by a consultant and was given an offer letter on a stipend salary basis. At the time of the interview, the employer mentioned that after the appointment of our administration director and discussions with him, I would be given the appointment letter. However, the process of appointing the director may take until next month. We have already recruited an account executive in our original concern and have given them an offer letter. My question is, should I wait for the director to join, or do you have any suggestions? Please let me know what you recommend.