FTP Permissions

[Andreas Wideroe Andersen]

Hi,
I'm running FreeBSD 5.4 STABLE and the latest Proftpd. I have a little 
problem I need help with.

I want about 10 users to have access to the same directory/subdirectories 
on the FTP server and all must be able to upload, delete and retrive (full 
access) to the files in these directories.

I want all users to have different usernames/passwords so I can log them, 
but all should have full access to the ftp directories.

How would I set this up? I've tried making all members of the same group, 
but I can't overwrite/delete files other uploaded.

Any help very much appreciated.

Thanks!
Andreas