FTP Accounts and File Permission\Owners

Looking for some direction on how I can handle FTP accounts for our web server.

We use ubuntu for our own web servers the installation is rather simple, but I have lots of problems using FTP to transfer files to the server. The apache server runs as www-data and the files in /var/www are all owned by www-data group www-data.
So the problem is I create another user on Ubuntu for our web developers to use and when they upload files to the server, these files become owned by their user. Then Apache has problems reading these files.

How can a user developer1 upload files as www-data from their filezilla client

Or how do I overcome this issue?

I appreciate any help.