In my new high-fantasy world there is a race of wasp-like humanoid parasitic wasps with a culture that adheres to a 'no-waste' mentality, extending to a mainstream veneration of necromancy as part of this.
Being a race based on wasps, there exists a number of castes that serve the interests of their society, the one in focus here are the 'liches' a sort of magically-inclined priestly sect. In their society they undertake the raising of the dead to serve in a variety of tasks. Furthermore, they have the ability to possess the undead through magical means, controlling them directly like a drone from a distance.
Knowing this, I have come upon a dilemma: How can I keep the liches from being able to possess the undead of other hive nations? Unlike real life hives, they are generally more or less countries, where citizens are allowed travel. In warfare, these liches on the sidelines can manipulate a variety of husks to aid in the fight from a safe distance.
I have thought about magical 'signatures' that bind the raised undead to them specifically, but this keeps me from allowing the liches from cooperation between them, controlling the undead within one group, while not losing time and an upper-hand trying to figure which undead is uniquely theirs. Perhaps their magics could be linked so to speak? Allowing a, pardon the pun, hivemind between them that gives them control of an undead unit they desire?