Whom do I include in a small claims lawsuit inNew Y? I have sued the owners of the firm, do I need to include their agent who breeched the contract?

I signed an exclusive sublease contract with a New York RE Broker. He offered to safeguard some valuable property which was on top of my storage locker in writing. I accepted his offer. Over a year later, after many requests for their return, the principal of the Managing Agency wrote me that my goods had been thrown away and that his agent had quit the company. I demanded $. He denied my claim and got the building staff to sign statements denying they had ever seen them.. (This was after the Agent told me in writing 5 times that the building staff had them in a secure place.) I filed a small claims action for $5,000 against the Managing Agent. Do I have to include the Agent who is no longer with the firm in the lawsuit? Will his emails to me be admissible as evidence in court?