Welcome to YT, I am glad you fell in love with this breed. but I have to say that I am surprised your friend left her yorkie with you since you have 2 Shiba Inus. While they are beautiful dogs they are also known to be prey driven towards small dogs and you often read it's not recommended to have them with small dogs. I would not be surprised if a reputable small dog breed rescue denied your application based on that.
Shiba Inu - Wikipedia, the free encyclopedia