First of all, I am happy you went and got her. She deserves a good loving family.
She is scared and confused... you can understand that. She doesn't know you or your family yet- give her a little time ( at least a week or so, then if you still don't think it's going to work out you can locate another owner for her)
I would isolate her in a room where she can see and hear you and your family, but doesn't feel endangered (remember she is scared...) let her spend some time observing you so she will see that it is ok. Your family maybe a little more "active" than what she is use to. I can only image what a 4 yr old dog would think the first it came to my house! With 3 teenagers, 4 dogs and supper on the stove cooking?? OMG- talk about chaos!! The kind of environment takes some getting use to
Maybe even leash her to a piece of furniture out of direct traffic, but in a spot where she can see what is going on.
As for potty time- you will just have to get a harness and put it on her and let her roll around and freak-out of a little bit till she sees she's not being hurt. You will have to put her on a leash to go outside- she will not like it a first, but that is what you will need to do. She will not trust you enough at first to not run off- you will have to keep her on a leash for her own good.
I do hope you will give her a little more time- yorkies are very feeling dogs and I am sure right now she is feeling very confused... just love her and give her time to come around.