Actual Sovereign Knighthood was Required for Eligibility to Apply to the Knights Templar

One thing few know is that only actual existing Sovereign Lawful Knights could become Templar. Exceptions could be made if your father had right to become a knight (under his sovereign or if that government was in exile but had lawful right in international law). Also you couldn't be admitted if you were born out of wedlock. There were no outlaws admitted, none with debts or conflicting vows or what would bring liability to the order. All bastard sons of the Kings/Princes etc were especially banned because that would create even more liabilities. So these were true knights with Royal protections, as they combined their secular knighthood with Sacred. I think it was good that their activists for Christ were so irreproachable. As Knights of real Sovereignty before they had joined, they had never in any way renounced their Sovereign / National Knighthoods. So they carried their weight above the bar.

It wasn't till a generation later that the Templar were flourishing that the Western Pope of Rome decided to endorse the order.

Also this was the battle flag of the Templar. Simply the standard of Black & White. I like this idea as truth is black & white.

As published by the House of Brunswick. From Statutenbuch des Ordens der Tempelherren

Basically you must be already at the rank of knight by your local government, or father was at least with the right to be a knight. This can be also de jure rights to knighthoods when an existing Sovereign Government is still alive as per international law but maintained in exile at least by usage of title, and that the head of house has not renounced claim for any period, and if dormant the usage of the name and title of the monarch must be continuous, without gaps of more than 50-100 years for valid sovereignty in international law / laws of prescription. This title would have to not have been renounced by law and must have a continuous claim / protest to maintain their sovereign government. Proof of this continued protest is often satisfied by by using the coat of arms without interruption etc.