New sheep riding an existing sheep
This is similar to another question I posted, but in reverse. Can I spawn a sheep (or any other entity) to ride another, existing entity, like a player or another sheep?
Best Answer
If you know the UUID of the existing entity, you might be able to do something like:
/summon Sheep ~ ~ ~ {Riding:{id:"Sheep",UUID:<entity-uuid>}}
However, I don't know how to get the UUID of a mob, nor do I know if this command will use the existing entity or duplicate it. Summoning mobs with a specific UUID could be weird.
Pictures about "New sheep riding an existing sheep"
Mutton Busting: Kids Riding Sheep at The Clovis Rodeo | Localish
Sources: Stack Exchange - This article follows the attribution requirements of Stack Exchange and is licensed under CC BY-SA 3.0.
Images: Gabriel Peter, Eva Bronzini, Camila Bou, Tatiana