Hello @David Rutledge
First big issue I see- Don't purchase properties with a broker that has pre-selected an Architect and claims to have plans "in the final stages".. whatever that means. You have not vetted this person or know that they are experienced and capable of accomplishing the project. From the start the Architect's "plans" should have been utilized as a basis and you validate them and/or search for another Architect for comparable services. Seems this one doesn't know what they are doing or is just too busy to handle your project.
Do you have a contract in place? What does it state about deliverables and times? What is the termination clause? I ask this since 99% of the time, the plans/documents ownership stays with the designer whom created it. So if you do start from scratch they will need to generate all the documents all over again. I disagree with @Bob Ritner in that since the project hasn't been filed yet, you do not need any cooperation or assignment from the current Architect. In the eyes of the City, nothing has begun. If anything, this is the perfect time to switch Architects before submission and the current Architect becomes the Architect-of-Record with the City. At which then Bob's words ring true after filing.
Also- Almost never is an Architect services/contract assignable. Ask, but I am very doubtful. If I am working for one party and ownership changes, my contract terminates. I am not obligated to any next purchaser. This goes for the plans/documents to. My contract says they aren't assignable either. Only for use by the owner whom retained my services.
My suggestion is to terminate the contract if you are unhappy with the services and they are not abiding by what you need. Ask for the base plans/documents so you can continue the project. He/She may allow this and ask for your to sign a disclaimer waiver. Especially if you are paid up for the Construction documents. If he declines, unfortunately you'll have to start over.
As I mentioned, this is the time to switch if this person hasn't garnered your trust in moving forward. It will only get worst as the project proceeds.
-Jared W. Smith, RA - Principal Architect at Architect Owl PLLC (Licensed in NY & CT)