specific custom mob teleporting

When you make a custom mob with two separate entities with one following the ai mob as the display model, you teleport the display to the mob right?
How would you go about assigning which display model is teleported to which mob when there's multiple of the same ones in the world?
I've seen an example from commandgeek where, for each new mob, a scoreboard value is added as unique ids.  This example is from a pretty old datapack though (1.16) so I was curious to see if there's any better way to do it in new versions