
I am not sure which sex your dogs are, although you mention that Bracken ( terrier ) is female, but is Bramble female as well. I have 2 patterdales and 1 Cocker as well as other dogs, but find that the terriers tend to want to be in charge. My other dogs are older and are so laid back that they have no objection to the terriers being full of themselves. There is no real dominance issues, but both terriers walk the walk so to speak.
Could it be that Bramble is a bit 'in her face' and Bracken is making sure that she knows her place? just a little bit of 'know your place woman' yet Bramble being a pup is so thick skinned she is not reading this and still insists on licking Brackens face etc. Knowing terriers I think if Bracken really did not like Bramble she would have turned on her by now. It sounds as though this is a little bit of 'putting Bramble in her place' in doggy language.
Hopefully as she gets older Bramble will accept that Bracken is more dominant and not threaten this hierarchy and a quiet life will be had by all.
Just make sure you are around to take Bramble away if she gets too much for Bracken to cope with while she is so young, because if 2 females fall out then sometimes there is no going back, and they will continue to fight for ever more - fighting females are the hardest to cope with as they never forget, so make sure you keep them calm and then separate if you feel Bracken has had enough.
Good luck