So your stepfather's daughter is estranged from him. Is she also estranged from you? The quickest and most straightforward approach would be to get in touch and ask her what she'd like to do from here. She can't transfer her POA to anyone, but if she agrees to resign it and work with you on guardianship for her dad it will make everything simpler.
If you do decide to approach her direct, avoid making her feel guilty about this. It's a purely practical matter. You may or may not have your own opinion about how she's handling her relationship with her dad but try not to let it show! Focus on what happens next, and not on how everyone got to here.
SueDillion, I assume your Step-Dad gave Power of Attorney to his daughter many years ago back when they were communicating with each other. Is that correct? Back before he developed Alzheimer's/Dementia?
I see from your profile that you live in Queensland. Does Australia have something similar to "guardianship" [which we have here in the States] where you ask the Court to give you full control over a love one who isn't able to care for themselves? If yes, this may be the route to take. Check with a Barrister who deals with elder laws.
Who appointed her as POA? If it was your stepfather, there is nothing you can do. It’s his choice. You would have to enlist the help of an attorney and have it proved that he was incompetent when he signed the POA papers to have her POA revoked.
Meanwhile, this is the website you want, I think: https://www.qcat.qld.gov.au/matter-types/guardianship-for-adults-matters/application-process
If you do decide to approach her direct, avoid making her feel guilty about this. It's a purely practical matter. You may or may not have your own opinion about how she's handling her relationship with her dad but try not to let it show! Focus on what happens next, and not on how everyone got to here.
I see from your profile that you live in Queensland. Does Australia have something similar to "guardianship" [which we have here in the States] where you ask the Court to give you full control over a love one who isn't able to care for themselves? If yes, this may be the route to take. Check with a Barrister who deals with elder laws.