multi game network

What I am trying to achieve here is our company is almost done with 2 games we have created. One is an MMOFPS and the other is a rpg type game with some multi-player functionality We want to bring these 2 game together.

Main menu(you login with your username and password) which ever game you have purchased you can play that game. if you bought more than one then you could play either one.

The main menu after the login we be like a interatve system where player can chat to each other and to friends(Like Real Id from Battle.net)

As anything like this be done before with unity?