Next of Kin

What is the name of your state? New York/Kentucky

My mother became ill two years ago and she is currently in a nursing home in New York and is not able to make decisions for her self. I reside in Kentucy, I am her eldest biological daughter (27 years old). She has two other children under the age of 18.

My mothers half sister feels that her and her husband are my mothers next of kin not me. Especially since I live in another state. My mother did not designate a power of attorney before she became ill. I do have a letter from the doctor that cared for my mother that states before she beame incapacitated she requested that I take care of all of her medical and legal matters.

What is the law?

Any insight will be greatly appreciated.