I wondered if anyone had any tips for me with this?
New puppy is lovely, next to no mouthing and no grabbing of people etc. She is 12 weeks old now.
Her and older dog (6) have been getting on well in the house, almost no arguments bar the odd grumble from him. She much prefers the company of humans anyway which suits older dog as he likes his own space most of the time.
The only thing I am struggling with is on walks when they are together. I am working on training walks alone but do go with both of them on occasion. She finds this very exciting as old dog is very driven and runs like the wind and she is grabbing/biting him constantly as he runs. She also tries to grab him on lead but I put a stop to this immediately- obviously off lead this is much harder as I can't catch her quick enough 
She will recall very well but he is just too exciting not to grab hold of as he runs. They are both a herding breed and so it is natural for them to herd eachother but it's only her doing the herding!
Sadly old dog won't really tell her off so I was wondering if there was a way to discourage this type behaviour? Poor old dog is getting fed up of getting nipped on the bum as he runs 