Hi Christy and welcome to YT! Congrats on getting your new pup!
We also have a mini schnauzer and a yorkie. Our schnauzer was here before we got our yorkie and, Hansel, is almost 10 years old. Because Hansel is so much older...it has taken some time for him to become accustomed to the new baby. Give it time...we actually took Hansel to meet her on the first visit then we also took him when we picked her up so he could be part of the process. I think that helped a bit. Please be very careful when your schnauzer is with your yorkie because they have a very delicate bone structure and can break something very easily. I wish you the best!
Good luck and please keep us posted and share pictures as soon as you can. We all love to see pictures of each other's pup's.