I'd like horses being ridden to teleport with the player when they use a waystone.

I'll note that FTB Utilities /home command generally transports your horse with your properly. Sometimes you get "stuck", but I'm not sure if that's related to the command or not. Perhaps they're using a different teleportation implementation.

I was curious as to how this might work...

I had some tweaking around with this in 1bc01c4. Moving just the mounted entity is sufficient with an integrated server, but there's some sort of timing involved with moving the horse and the client/server player location updates which makes it unfeasible in a dedicated setting.

Indeed, in the dedicated setting I was able to move both the mount and the player (with the mount arriving shortly "after" the player, but that may have been lag). Attempting to forcibly remount caused it to cease working entirely.

Really interesting... definitely something that I'd love to see as an option, even if it did involve being dismounted.

I wonder if there some event that's lurking somewhere for when the server properly updates and broadcasts the locations of entities that could be used to remount the player. I really need to read more about Forge.

I think it would be an improvement if it dismounted you but teleported the horse still. You'd have to remount but you wouldn't lose the horse

I know this hasn't been touched in a while.... however I too want mounts to teleport!
However, the built in teleport command, takes RIDERS with it....
So, if you click a stone, see if they are mounted, if they are mounted, teleport their HORSE, and the rider moves with the horse.

Now I'm not sure if this works with forge's API, but executing any command block on a mount you're riding will move the player with the mount...

So if forge lets you just pass any MC command, problem is then pretty easy.

Entity riding = player.getRidingEntity();

Then send the mount to the target location using default minecraft code?

Still getting this in 1.16.5-7.6.2.jar