Congratulations on getting a second yorkie. Atticus is a real cutie. I am sure Cooper and Atticus will get along well. I am so glad that we got a second yorkie two months after getting Duncan. They also are two months apart, just like yours. Duncan is 10 lbs. at the moment and Elliot is 4.5 lbs. but they get along very well, playing together and rolling around on the floor. Duncan seems to know that Elliot is smaller than he is and that he has to treat her gently. They are such good company for each other.
Good luck with being the mommy to two yorkies