[yorkietalkjilly]

It's perfectly natural for them to go through this as you already know so follow Mother Nature and let them work it out over time as they would do in the wild. Often new members to a pack that aren't born into it are ostracized and tested - frequently. It's just what they do in order to test out the new member in all circumstances to see if this one should be added or rejected by the pack.

If the new member is basically unstable or has problems, the testing eventually proves they should drive the new one away so as not to endanger the pack due to some insufficiency in the newbie. But if accepted, the new member is slowly assimilated into the group and over time, becomes just another member with a vital role to play. Where there are only 2 in the pack, the more submissive and stable the new one is, the quicker the testing phase and acceptance but where there is a nervous new one or one that is perceived as weak, fearful, dominant, aggressive or some other undesired trait by the existing pack member, it will take quite a while and may never perfectly gel. Still other times, the new one that is more dominant may very well over time supersede your older dog and slowly become the pack leader and your older dog start to give way to the new leader. There could be a fight or two in the process but if they aren't too vicious and there is no real biting taking place, just bared teeth, a harmless nip or two, loud growling, barking and tussling, I wouldn't interfere. Dogs get loud when skirmishing and doing test fighting. Dogs use their teeth oftentimes as we use our hands or fists and if we slap someone, it's not the same thing as choking or a vicious blow to the nose with a balled up fist. So just because you see teeth, a nip or bite that isn't hard, think of it as a slap or hit. Just watch for the hard bite or prolonged attachment which represents a savage fist blow or choking and intervene to prevent injury.

Usually it won't come to that unless you have two dominant dogs vying for alpha roll and if that's the case, it will take time for them to work out some type of mostly peaceful coexistence, with occasional fights along the way. Most neutered/spayed dominant dogs in a pack of two with a strong pack leader human will soon learn vicious attacks are never allowed and work it out, though they won't be best buddies ever.

But most housedogs are eventually very glad they have a true canine pack member join them in the home in time as they are extremely social pack animals and usually love having another canine presence in the home. I imagine it's like living in another country where the people are lovely, you have wonderful new friends and you are doing great with no complaints at all but having a nice American from your home town who knew your family move in next door is better still. And even if she has one or two things about her you might not be happy with and those take some adjusting to, it's still really nice to have her there. And if she turns out to have your same ways and interests and give you lots of support and friendship, is always there for you, you'll be thrilled for your friend from home.