I've attached an image thinking it will clarify my idea.
I'll be having about 10 different groups, each group will be having their own news, blogs, images and users. Each group will have their own unique content and should not be able to look at another groups content (Group A will not be able to see Group D content, especially users).
Looking at your response, I know now that it is not possible for each group to have a unique landing page, unless I implement it.
Thanks for pointing to the right direction.