Parents

Has anyone had to step in & deal with aging parents issues? I am concerned with my mom, since there is a history of Alzheimer's  in her family. She has made some real STUPID decisions lately & she doesn't comprehend the repercussions with making these decisions. She just came into a lot of money, from an insurance payout & I am afraid my greedy  step-siblings are starting to ask to borrow money ( or should I say borrow more), I am afraid she wouldnt say no & they have a history of not paying back. One had her co-sign a house loan& I found out this week they haven't paid their taxes since they bought the house  and now it's in foreclosure. So my mom has to pay them to avoid it hurting her credit even more.

So my question to you, at what point do you have to step in& be the "parent" to your parents?