when you get another pup,keep it on a lead or rope 15-20ft long. then let go right by them and if it shows to much attention them ,give it a yank with firm NO. Keep doing this till it stops . With lambs still the same, but it might be a bit harder, as lambs are smaller and (move) differnt to sheep eg bounce around, which alot of dogs pick up on. You can still do it , just keep a eye on it. I have + do lamp with sheep there, but they are a feckin pain, as most times they get in the dogs way on a rabbit . I prefer to go where they aint any if possable, as i can catch more rabbits