Can a nursing home use their own discretion in medical care for a resident over the request of the family

My mother is living in a long-term facility. She started showing signs and symptoms of Covid. She had a horrible cough and a fever. My sisters and I requested they test her for kovid because it was in the facility and three residents already died. They never answered us. when we requested again we were informed that they will only test when they test the whole facility which is weekly. My mother stayed sick for 5 days before they tested her when they did the facility and it came back positive She ended up in the hospital in ICU on a ventilator and now she is in hospice dying. when reading the CDC guidelines for nursing homes it says clinicians can use their discretion. I would like to know does their discretion override our request for the welfare of our mother?