[JoeyP]

I think this is somewhat complicated because the older dog has a history with you and your house
But if you introduce them slowly and correctly there shouldn't be a problem

Have them both be on a lead
bring them into a large room with one person with each
do not put them face to face
let them realize they are there
if there is barking have them re-enter the door
and start over
if they are good treat them
and then slowly bring them closer and closer

I would have the older dog smell the rear of the younger dog since she was the one giving the problem

That is a less intimidating intro for her

The whole time have treats on hand