Organization of a New Pool

[Just Curious]

A group of registered Montana officials have formally started a new association. In Montana, the ratings are Apprentice, Certified, & Master, with Master at the top of the food chain.
Forming the new pool, creating the hierarchial structure, following State of Montana protocol, and getting games through the local Middle & High Schools has gone smoothly.
However, our first stumbling block has come with upgrading.
Question: How does one upgrade members to a higher category when none exist, in name, at that grade level within the pool?
We have two Certifieds within our ranks with the rest of our membership as Apprentices. I doubt that the upgrading of the Apprentices will pose a problem, but moving the two Certified's up will.
Over the years, new pools have formed. But these have started with a nucleus of Master officials.
Surely this situation has happened elsewhere. How did it evolve? As this forum is a valuable resource to me, any & all suggestions are welcome. TIA