Samsung Devices - How to prevent missed calls & SMS from bringing back the stock widget

Samsung pushes its own stock widget whenever there is a missed call or an unread SMS message no matter what lock screen widget is used as primary widget. 

Unfortunately there is no way to prevent from missed calls to do that, but if you'll use a different SMS app instead of the stock one it won't push Samsung's stock widget. 

Sliding Messaging app is very recommended since it has action buttons such as Reply, or Read that will appear on NiLS too when notification arrives.