Mayeux suggested an outer spy and inner spy.
Inner spy come from them; outer spy is spy of convenience. If they were caught it is not a loss, and if they are not caught it is an advantage.
As for loyalty, there is not much to change.
There is personal bonds and shared tribal affiliations.
Tribalism is bad in a multicultural empire.
But to unify a and form a nation or an empire, the use of such tribal affiliation could not be dispensed.
In Aeryon own history there is many empires and kingdom that started that way. There is Genghis. Tamerlane. Qing. And that is to name a few. The only difference is when it became an empire, could it reform itself?
But that is too far from Aeryon right now.
As for other method to retain these realties, Aeryon suggested that there should be a reward for rewarding loyalty.
Loyalty mechanism could be used by those emotional bonds. But incentives should also be given.