I believe you may have the organizational structure of Amtgard a little mixed up. The way we work, is that every land (anybody who has officially organized and is playing Amtgard in a unique location) must be contracted with the Burning Lands BOD. They control the copyright for Amtgard, and you must have their permission (through a signed contract) to utilize the Amtgard Rules of Play and/or call your group Amtgard.
Each land or collection of them can be promoted to various levels. Each land starts at a Shire, may advance to a Barony, then Duchy. A collection of lands or single really large land, may form a Principality, and eventually become a Kingdom if voted in by the Inter-Kingdom Circle of Monarchs; composed of the kings/queens of the 14 Kingdoms of Amtgard located around the country. So Wyvern's Spur is a shire, and I recommend due to proximity, your work with them to help each other grow. As for where the Rules of Play identify you must seek permission of the closest Kingdom to join a different Kingdom (Kingdom Boundary Section), that Kingdom would be the Kingdom of Dragonspine based in, I believe, New Mexico. Here in California, we have formed the Principality of Westmarch, which operates like a Kingdom, but without the same level of authority/representation.
So, to wrap it up:
Starting a new land only legally requires the permission of the Burning Lands BOD.
I recommend you get permission from (and join) Westmarch and Dragonspine (Westmarch's Parent Kingdom).
I strongly recommend you work closely with the members of Wyvern's Spur.
Additional reading I recommend is the Westmarch Corpora. Located
here.