Read/Write Folders

I would like to set up a folder on our server form picture sharing. I have asked it to be set up so that a group could drop pictures and everyone in the group could read them. But I would also like it so that the group members could only delete their own files and that only admins could create and delete folders within the original directory. I am a school admin, my tech department told me this was not possible on a mac server.

My question is it it possible and if it is can someone tell me how or point me in the right direction so I could share with tech team.

Mac server 10.6 clients on 10.7

Thanks,

Phil