So I read several posts and the thing i noticed is, most don't understand that there will be no paradox.
This is not intended as a vehicle to change the past.
The danger for the present timeline is in the form of the Orcs coming through the portal in mass.
Everything we do in Dreanor we do to prevent them from going through the portal to the Present time, we are not preventing them from going through the portal the first time.
This is a clever way to prevent the usual and much dreaded time travel reset button.