How are you?
need to update from GCM to FCM for notification?
OK. I can help you easily in short time.
I have a rich experience of firebase development.
In general, FCM notification has 2 option- data message, notification message.
To catch all notifications in mobile app, prefer data message.
..
Anyway, I want you to discuss about project any details via chat.
Hope your reply. Thanks. From LS.