I had and sometimes I still have issues with Hot Rod and Maggie May. I make sure to give Hot Rod any type of attention first. feeding, treating, putting harness on first, etc. This seemed to help some but now they are in a constant battle to see who can get to mommy first. lol. The actually go under each other when they are giving me kisses. (they stand on the sofa when we put harnesses and jackets on and when I get home from work. I can' even tell how they do it, but all of a sudden the other is right in my face, lol. We had to yell at Hot Rod as he will pull Maggie by her topknot!!
Give it time, Cody will learn to accept Chloe. It is funny, when one yelps, the other is right there.