How do we legally get control of mother-in-law to manage her finances?

My wife and I are dealing with her mother who is undiagnosed BPD. She has had all the HX depression anxiety 1.5 years ago She OD ednon klonopin She kept calling me to help her sort medication bc she had dropped bottles and they fell out. all she was doing was building a back story to why she was running short on klonopin She substituted it with a blue Bentyl pill in the bottles so I never caught it she seemed to be not using all of them. Until I looked closer after the fact I would have thought dementia and pills that looked alike but she was able to back count and refill correct number of pills she should have left for that day of month that takes though So she OD I found her at home with a wrist that was at a right angle and bleeding I sat her down on the couch and left to drop kids who were in car I got back she had a head would oblivious to fact she was in bad shape . I took her to ER and they treated her she did rehab yet still was confused on D.C. 3 months from time of OD Everyone said she had dementia and if I didn't know how long Klonopin can take to clear I would not have believed it It took weeks and by then she was given anti anxiety meds to treat what I imagine was withdrawal unknown to them I found evidence of doc shopping and other signs of addiction So she was D.C. And we were told she can not be alone we found her the best senior care w rent control amazing place she was so lucky to get in . Then we got her a wonderful aide who stayed 24 hrs plan was for couple of months and sell her house to pay for care well she recovered wonderfully totally with it we managed her life we found out she ran out of money and could not make monthly bills And that led to this OD Well she refused to give up care so we payed and she seemed to be going along w giving power of attorney to my wife and we were to sell house we had appraisals and met w realtors and she didn't sell she finally told us she was ready in march of the next year 7 months since she started 24 hr care and two residents Which ran in total 12-14 g a month . She kept this up till April when we stopped giving her money and he son agreed to only pay for day time aide She is AOx3 can ambulated w came no reason for 24 hr care We had an aide in every day Still her bills were 7-9 g She finally sold home 17.5 months later after I got work done on it and sold it I ve been one to manage everything bc her relationship w my wife is awful she said she can't deal and I felt better me I m removed and wife doesn't have to feel guilty So we go on and she is cleaned out of saving s she keep saying more money exists she had to use charge cards I agreed to charge our items and give her cash to pay bills until she got fuzzy about the arraingement Feeling paranoid I taped out convos thank god bc she denied knowing any of this and it would have looked like I went to town with her charge cards . We gave her 49 g over year and half we have 4 kids my truck isn't working we can't afford to fix it til her house is sold no prob I'm using her car she can't drive now she tell s people I took her car We took her money The only good thing is I kept her sons up to date on what I was doin w money each month sendin a statement and had all 3 kids agree to what she had when I started . She is unbReable Refused to have food deliverd bc I asked her to to save my time she tipped a dollar they stopped coming She now send aide on a bus I found out it takes 4 hrs at 19 hr It's insane She s make lot she of bad choices has no money and now claims it's all because of us We ve been managing best we can we have had oversite so no issues w her claims of us taking her money She tells sons she has issue s w us and money then when sons tell her she has no money that's the issue she tells them there two sides to every story She has had emmence spending happen she had to lay out money to clean out her house and she had to have her stuff moved and house needed repairs she has credit card debt through the roof . I fixed house sold it for a lot of money thank god now I want to set up a trust and make sure her money is protected to save her going to a nursing home. She says she doesn't trust us so we ask her who can we do this with. She gives no names lawyer says outside manager will cost to much we r at an impasse She is a person with classic borderline personality I know this I ve seen her behavior I think this is that but at times I wonder if dementia isn't the problem and do we need to get her on meds to help her for that Or at least find out if that's it I could cope so much better if it was dementia and not personality driven Long venting here sorry What we need to know is how do we get control of her legally to manage her finances and care we have power of attorney we have medical charts saying she has dementia from nursing home but she signed power of attorney then so we want to have her evaluated she plans to revoke our power of attorney and go it alone