Very good story, something that I have never read about. How does harry reached the teplars, Im guessing maybe james or Lily Potter were part of the Order.
Since this won't give anything away, James and Lily weren't members of the Templar. As to how Harry reaches the Templar, if you notice he does a Templar version of Apparation (The burst of golden light). Its slower than Apparation since he has to channel the magic before he teleports, but it can bypass apparation wards since it isn't apparation...just a little fun fact for everyone