Application badge on notifications

I’m using gcm to send notifications to users, only two issues I come accross: Sending the badge attribute with a number works fine. Looks like badge shoud be menaged server side. Is I do not seee a possibility of sending one message so it will be broadcasted to multiple users if a badge should be maintained server side.Another issue is when I open an app if I have a notification, the notification disappears ad will never be processed in the application.
Please, someone help.