I'm not terribly experienced, but have had three working collies. I've trained Dot from scratch, bought Skip part-trained and have brought him on, and Ted arrived knowing what to do but with no commands whatsoever

I think they're all pretty useful dogs now

And my BiL thinks so much of Skip he borrows him every February to go lambing with him now his own dog is too old.
Collies are obsessive, they're bred that way. If you had a dog you wanted to work that wasn't obsessed with sheep, you wouldn't want it to become obsessed with an alternative. Dog trainers working to manage sheep-obsession in non-working dogs will try to develop an obsession with balls (or ragger, or squeaky toy, or anything the handler can control the dog's access to), then use the object of the dog's obsession to distract the dog from the sheep. So as a general rule, one wouldn't want a collie that's to work to get too interested in any toys.
Some people also think it will harm a collie's outrun (where it runs out in an arc to skirt wide around the sheep and get to the other side of them before coming in to bring them to you) to be running straight after a ball or other toy.
But, they have to be puppies and they have to play! So a bit of fun with a few different toys, a bit of chasing and fetching, won't hurt. As your dog is clearly very interested in sheep, you probably wouldn't be able to override that obsession in any case. So I wouldn't be too upset about it, but I wouldn't do too much of that with him yourself, I'd leave that to be a game he plays with your daughter.
However, my main concern with what you've been doing is that with a working collie, all training and all training words really need to relate to sheep. It's a mistake to start teaching
any of the working vocabulary in the absence of sheep, with the possible exception of '[come] here' and a heel command, as these two alone are the same in the presence or the absence of sheep.
"Come Bye" doesn't mean "Go left", it means "Go clockwise round the sheep". Depending where the dog is when the command is given, it may have to run right to get to the sheep and go clockwise around them. Similarly, "Away [to me]" doesn't mean "Go right", it means "Go anticlockwise round the sheep."
"Walk On", doesn't mean, "Walk forwards", it means "Walk towards the sheep."
"Lie down" doesn't mean the same to a working collie as it does to a pet or obedience collie. It does not mean "flatten your body on the ground where you are and wait for another command." It means "focus on the sheep; lower your body; remain focussed on the sheep and don't move". In other words, when a shepherd tells his/her dog to "lie down", the dog should stop moving, usually lower its body or lie down
facing and looking at the sheep. Most shepherds have at least three "Lie down" commands. All of them sound like "Lie down" to a non-shepherd. (1) means "focus on the sheep, pause"; (2) means "focus on the sheep; stop and lower your body a little", and (3) means "focus on the sheep and lie down, really lie down". That's one of the reasons a lot of people think many collies are "hard to stop" - they hear the shepherd calling, "lie down .... Lie Down! ... LIE DOWN!!!!" and think the collie ignored the first two commands. Well, it may have done, but equally likely, the shepherd was bringing the collie slowly onto the sheep, slowing it as it gets nearer, so as not to spook them. On the final "LIE DOWN!!!!", the collie should have the sheep under control from the prone position. If it'd stopped flat on the first "lie down", they would have known it was too far away and couldn't stop them and they wouldn't have been under control. If it'd approached without that slowing, they would have spooked and run away, and not been under control.
So, Steve, I really wouldn't be teaching your dog any commands you want to use with sheep while you are playing with him with the ball. In fact, I wouldn't be teaching him any commands at all except a come here (come straight to me, in a straight line, no matter what obstacle is in the way) command and a walking to heel command. Maybe a "drop it" command. (Don't use "That'll do" for that!)
Collie-training works best when you let the collie do what comes naturally and then tell it what it's doing. So let it run round the sheep; as it moves clockwise around them, tell it, "Come Bye"; as it moves anticlockwise around them, tell it, "Away". You get it to change direction without a spoken command by using your body to shift the sheep so that the dog changes direction to compensate. Then tell it what it's doing. Gradually it learns to associate the sound with the action and you can start to give the command ahead of the action. There are other ways to train collies, of course, but this one works well and fast, involves no compulsion and no retribution, and results in a collie happy in its work, so it is my recommended way. Oh, and I learned it off Derek Scrimgeour - it's his recommended way too
Working a collie on sheep is not like obedience or any other discipline I've experienced. You're a team, partners; you need to rely on each other and trust each other. You don't give commands, you make suggestions, give invitations. Your dog may well take your advice, but sometimes it may not. It may be able to see something from where it is that means your suggestion isn't the best thing to do. It may not understand how the suggestion you've made is useful in the current situation. (An experienced collie is always thinking ahead, so if it doesn't understand where the action is leading, it may not be able to see how to do it. And it
always knows what the sheep might do next, and how it will counter that.)
I'm getting a little ahead of the original question now, so I'll curb myself (lie DOWN, Sally) and give you a chance to read and absorb that.
I was thinking the other day, how owners always look like their animals, and wondering in what way, then, I am like a collie. (Since I am certainly not fast and wiry.) I realise, reading this, that, as a collie is obsessed with sheep...
