which family history counts breast cancer

I am trying to find out which members of your family do you count if they have died of breast cancer. Is it just our parents and their parents or would my grandmothers sister and her daughter both passing away from breast cancer have any bearing on the risk factor for my sisters and myself? I was not aware of these relatives having breast cancer when I was diagnosed and did not mention them to my Oncology team. I want to explore any information like that for my sisters and mother. Thank you