My take on it....-
Lamps: Who says you cannot lie to Prime or Main Vendors? It's same for all - Prime vendor or Mid or main consultancy. Even for direct client hire. I am not suggesting to do one or the other.

These days even hiring managers knows about these resumes with 7 years of experience... As long as your perform to their expectations and make your job done, they don't care.

Things would be different if your go in H1B with direct client since you have to submit original resume.

Your current Prime vendor have your resume for your current job and they believed that. SO If I were you, I would just add the recent project and use the same resume. There is no proper way anyone can verify your work experience like your school degree or Credit history. It's all references. And you can always find those references.

But, there is always a clause in your contract between these Prime vendor and mid consultancy and same applies to your main consultancy. Usually it will not allow you to join prime vendor or even mid vendor for a certain period of time. I have seen contracts
without one too. So it all depends on the contract and sometimes companies are easy on it too even if there is one.