My sister has always had a history of taking what she wants. I have everything in my favour legally to protect my mother, but off and on my mother forgets and when my sisters asks she will give her something, a chair, a painting, but then later she says where did that go? She also has a habit of going in and taking things when we are out of town.im going to change the locks and not give her the key, but I want to tell her my plans in advance in a diplomatic manner. Oh by the way my sister has personality disorder so I'm also dealing with serious mental health issues and want to be sensitive to that as well. I'm trying to keep the peace but am tired of my sister taking advantage of my mother.