Most dogs, and Yorkies in particular, tind to bond with their people. Yorkies do seem to be much more attached than many breeds and are so very sensitive emotionally.
The best way to redirect her to your daughters is to have them act like the owner or some would say "pack leader." Make sure one of them feeds her
all the time and have them comb her daily and give her treats. They can try taking her to bed with them at night and taking her for a walk a couple of times a day will go a long way as far as making a loving relationship. When your little girl learns that your daughters are her family she will want to be with them.
My problem with this is that as your daughters get older they are going to be busy with school, activities, and their friends. It is inevitable. That could cause some problems with your little dog. Mine gets depressed whenever one of her two favorite people leave the house.
You have chosen a very emotional breed so make decisions carefully about her future.