How do you add someone to a HIPAA form?

How do you add someone to a HIPAA form if the original person listed on the HIPAA form is now deceased and was the only person listed. The patient is 90 years old and in the hospital with complications from a stroke. The original person listed on the form was my Mother's brother who passed away. His wife is now getting information from the hospital, but my mother needs to also be allowed to speak with her mother's (the 90 year old patient) doctors.