Balking Ponies

Question
Hello again!
I contacted you once about the two ponies I am working with. So, one of them, Toughy, is about 16+ years old and an absolute angel. The other, Snipper, is (well, the opposite!). Snipper is a definite handful (yet fun to work with), so I have a few questions.
(1) How should I respond when I am trying to walk Toughy around the paddock and Snipper is trailing behind nipping at Toughy's sides/face/etc and neighing for attention? I work with Snipper first to get his attention in, but once I turn to Toughy he gets upset and starts having a fit. Currently I put my hand on his nose and stop him from moving forward, while at the same time leading Toughy away from him. Also: I am not able to work with the two anywhere else then their paddock. I cannot separate them or have another person in with me holding Snipper.
(2) Snipper balks when being led by a halter and lead; am I responding right by doing the following: I didn't want to have a tug of war (obviously he would win) so I turn him on his left and as soon as he got his feet moving, I got him in a forward motion. I automatically praised him ("Good boy, Snipper!") and patted him as he walked, which he enjoyed. Just as his feet stopped moving and he balked, I stopped praising him (which he did not enjoy). Then I turned him and started forward, and I praised him once again as he walked. This time there was an improvement, he did not stop but instead followed me and continued walking. We walked in a square formation until I said a firm 'Ho!' and pulled back once on the lead. He stopped and I praised him.
This appears to be working (he actually listens now) but I cannot get him to start moving forward, I have to turn him. He also crowds me as we walk, and he sort of wavers between my right and left (though I always lead horses on their left staying a few feet in front of them, as this is how I have been taught).
(3) I need tips on how I should respond to his nipping! Right now whenever he tries to nip my leg (though he does so slowly and almost gently, but it still hurts) I push his nose away, which makes him stop for a while.
Also, you should probably know these ponies' heads reach my stomach and I am 5'7, so they are pretty small to work with and it is difficult to me when I am used to horses that are taller than me.
Sorry this was so long, I will be super pleased when you answer ;)
-Sarah

P.S When I brought apples to feed them (I always do) Toughy nickered at me (I think)! I have never been nickered at before!
These Shetland Ponies are super friendly and love kids the most, they whinny at everyone and adore being pet. Its so cute ;)

Answer
Hi Sarah,
It sounds like you have the right idea when it comes to teaching your pony to lead. Don't worry too much about the formation you are walking in, just keep your pony a bit behind you and walk off like you have somewhere important to be. The only release the pony needs is that when you are leading and he is in the right place there is no pressure on the lead rope. As far as Mr. Nippy I would practice keeping the one pony with you and behind you a bit as you send him away. You could use your lead rope or a lounge whip. If he is not close enough to bite you he wont, and it is your job to show the other pony that if he is with you you will protect him, he is safe. It undermines your relationship with both of them if you let them get into it while you are there. Try this out and let me know how it goes.
Best Wishes,
Caitlin Day Huntress