I've got calls into my local association to get their advice as well, I've gotten conflicting information from several brokers here in IL...
California law does not allow real estate licensees to prepare or explain the real estate legal documents without the real estate practice in the same transaction. For example, based on the same scenario you have but in CA, you prepare and explain the purchase or lease agreement for the buyer, seller or leaser or leasee but you did not list the business or you did not show the business. That is equal to Unauthorized Practice Law (UPL). In CA, it is illegal. I do not know if it is crime. I guess so.
In NY, they have real estate lawyers to involve the paperwork. In CA, real estate licensee can do that but the condition is you should have practice in the transaction as a real estate person.
In this case they have a lease for the business, they are not selling the building. Your broker may also have a concern about Errors and Omissions Insurance coverage. Do you have expertise in selling businesses?
Depending upon the situation perhaps you can refer it to a commercial broker, or have one oversee the transaction.