ftp forwarding by any other name?

I have a number of websites hosted on a single server account, no problem there the hosting company are quite happy with that.

Thing is I need someone else to upload the information for one of the sites but there is only one ftp account (apart from the anonymous ftp accounts associated with each domain).

Im a little sceptical about anonymous ftp, it seems to flaky and vulnerable to be anything other than a bad idea.

I dont want to give this person the ftp details for the main account, is there anyway to automatically forward the files to the main account?