I was talking with russetfox12345 earlier and I came up with a great idea.

Since no person can physically be in two places at once, the elves could have gem pendants to use to be in two places at once ((for example my character Rhys's brother, Russet's character, is hospitalized in the human kingdom and Rhys promised not to leave his side, so this is a way that such a promise could be fulfilled without both parties physically being there. All one would have to do is mutter an elvish incantation ((I'll eventually get the vocab up for a reference point if Russet is okay with it)) and they are projected as a hologram to the other person.

Here's a pic to show the gist of the necklace. It would also glow when being used