Providing FTP access to site for client...

I have a site we are hosting for a client on our company's server. The Sitefinity version is 5.0 Small Business Edition and the IIS version is 6.0.

I developed the site, but the client wants to use a 3rd party Sitefinity developer to modify the site. Giving FTP access to the IIS folders is easy, but I don't know how to allow them to make SQL changes via FTP. I could modify DataConfig.config to attach to a database located under App_Data. That would give any developer access to upload the mdf and ldf files. But how can the 3rd party developer detach the database files, upload new ones and reattach them. If the database is still running, FTP access to the database files will be denied.

I've never personally worked with attached mdf files before and always use a server instance. But that is out of the question for 3rd party developers as only FTP access is permitted. 3rd parties can directly use any SQL tools to access the data.  I can't see a solution without our staff personally intervening and shutting down the site when a new database needs to be uploaded.

My boss is looking for an answer by tomorrow. Our company has never acted as a hosting provider giving unattended access to 3rd parties.

Any suggestions?