I don't know much about bash scripting, but it should be possible to make yourself a script that could perform that task?
For as far as I know, you _have_ to (temporarely) put the files on your local system.
echo 'user yourusername yourpassword get foo.bar bye' | ftp ftp.middleserver.net 150 # get files from middleserver
# if you still want foo.bar to be uploaded somewhere else, try
echo 'user yourusername yourpassword put foo.bar bye' | ftp ftp.lastserver.net 200
Note that the bold
tags need to be altered to the correct forms that apply to your environment.
Hope this helps in any way.