We just brought another yorkie into our home after having Jake for a year. Jake is very spoiled, and is a huge mama's boy. He wouldn't have anything to do with me for a couple days when we brought Jackson home. He didn't seem mad at my husband, even though we both went to get Jackson and took Jake with us.
I just made sure (and still do) that Jake got lots of attention, just like the new puppy. I also made some extra time just to spend playing with Jake. My two are still jealous of each other, mainly when it comes to me holding them. I've just had to be extra patient with both of them, that's all. They play together ALL the time and have so much fun and seem to really love each other now. At first, Jake wouldn't stay on my lap if I picked Jackson up. But, now they will both sit on my lap or lay all over me at night time when we're sleeping.
I think it just takes times and patience, until they get used to each other. I let them work it out and have never interferred, unless I thought one of them would get hurt. I think the transition went pretty smoothly, and I don't regret getting the second one at all. I still have a very close bond with Jake, he still is a mama's boy and still follows me around. The only difference is now I have TWO of them following me.
Both of them are such mama's boys.