so I'm new to GCM and our project involves 3 different apps for 3 different type of users, namely: Student, Parent and Faculty. So the use case is that the Faculty cancels the class for today, and will send push notifications to all Students enrolled in that class. Now I've been reading and watching videos about GCM, and as far as I know it needs to have a unique key for the application that will send and receive the notifications. In this case, the sender of the notification is the Faculty app, and the receiver is the Student app. Is this at all possible? Or do we have to unite these 3 apps?