Throw a splash potion of weakness at a sheep and feed it a diamond by right clicking. Wait for it to eat an ore of whatever. Now it is an ore sheep. They should not despawn as they are passive mobs and are utility mobs.
No idea, as neither the curse client nor the mym client can generate a world on my computer. I submitted a report about the oresheep despawning to the ftb forums in case it is a modpack issue, but it might be a server configuration issue so I wanted to cover both bases so a solution can happen as soon as possible. If it does turn out to be a modpack issue then this thread can be closed or whatever, and I would be sorry for wasting anybodies time.
Sad to break it to you buddy but that does not work they still despawn even with a nametag, the only thing you can do is use a method like a safary net or some mob capture device
Yea the only viable option is too make a bunch of safary nets and capture them before you log off for the day
Even with that, if you crash or get disconnected or the server restarts then there is a chance they can all despawn.
