Is there any way to stop the sell of my family's house?

My dad was trustee. Him and my uncle are 50/50 owners. I was assigned to take the place of either should anything happen. My dad was diagnosed with dementia house went into foreclosure and sold the house for money against my grandparents wishes when i couldve bought it. I tried to seek help from a lawyer but they needed his medical documents. I talked to his doctors and they needed his release. He stopped going to the doctors and wouldnt tell anyone his medical problems as he became violent and irrational. He just recently signed paper to sell it but i believe he is in no condition to make that decision. Is it too late? Or can i stop it? I have till the end of January. Thanks for any info!