We have a 10 month old boarder terrier and have just added to the familly wiv a 8 week old jack russel both dogs. Our boarder although not herting the little one seems to be put out by his arrival they play rough and lite bite each other. Little one yelps when they are puled apart they still continue. Will our wish come true of a harmonious household

They might need they're knackers off usually calms them down sorry couldn't think of the right term

Neutering, while a good idea for the 10 month old, probably won't do much to calm their play. It does sound like play, which with two terrors (sorry, had to leave that misspelling in) can get very rough.

If it's rough play I personally wouldn't have an 8 week old puppy running with the 10 month old yet.

What is the size difference between the two? (weights?)

I have 2 and 3 year old Miniature Poodles and I just got a 3 month old Chinese Crested puppy.
There is no way I would let the poodles play with the Crested until he is older and larger simply because an 8kg Poodle can do a LOT of damage to a 2.5kg Crested.

I'm not saying you can't have different sized dogs together, just not as puppies when there's a risk of permanent damage.

I'm not saying you can't have different sized dogs together, just not as puppies when there's a risk of permanent damage.

Yep. In some cases size DOES matter.