so what i would do is setup an admin user for each group. in your db users table, you could have a field for group. so when a user logs in and goes to your news creation page, you already know what group they belong to.
when they add a new news item, put that group in the db field on the same row as the news message.
on your individual group page, just read from the news table and only print the articles from that group.
you would only have one news creation page and one database table hold all the news articles.