[nana911]

I think chihuahuas and yorkies are great together. When you come back from your walks make sure Chuchi enters before the others. Maybe kick the kids out of his bed. It's hard to be 'forced' to share EVERYTHING all at once. Entire house, all the toys, you and mom! Perhaps you could manage a way to let his bed be kinda 'sacred' just for him. At least until he totally accepts them. Right now he thinks it could just be a playdate and he's waiting for the little buggers to leave so he can get his house back. When he doesn't come like usual, go get him and put him in your lap, or his usual place in the chair. Let him know that their presence doesn't affect your relationship or his place in the 'pecking order'.
The newbies will entertain each other, while you lavish more affection on Chuchi than he knows what to do with. Let him feel smothered. He may associate their arrival as a great thing if it brings him so much extra attention.

Congratulations on expanding your pack... the more the merrier!