My bother and I are POA for my mom. Behind my back, he went and had a will and a living trust done naming him as the executor/trustee. The will/trust benefits him and his children. I agreed to be POA to keep him honest, but he has done things without my knowledge. Now he got her to do a grant deed where he was added to the deed as joint tenant with rights of survivorship. I found out when I went the records office. My mother had no idea of what she was signing. She doesn't speak English. I feel he manipulated her to sign the form to keep everything, since we have 2 other siblings. Can she change the grant deed to get him off? I read that California law requires his signature to make any changes, is this true?