Creepy caregiver. Any guidance?

My dad was released from the hospital 10 days ago. Before his release I secured a couple caregivers thru an agency so he could have an easier time at home. One was an LPN, the other is her daughter. He lives with mom who is creeping into mid stage Alzheimer's I have a wonderful CG who comes in for mom a couple times a week. The two CG's I hired for dad were only supposed to help out for a while until we could see how fully dad would recover from systolic heart failure and pulmonary emboli.

Dad just fired the LPN, claiming he didn't need her. The non LPN CG professed to be a fabulous, healthy personal chef which appealed to us because of dad's new no sodium diet. This CG, however, has made herself indispensable to dad, doing everything from cleaning out the garage to refilling bird feeders. Sounds great, doesn't it.

Unfortunately, here is the problem. My dad is overly trusting. He's well off. He's not incompetent, just vulnerable. This gal has worked her bum off to get close to my father, to be his right arm. She argues with me about medical concerns even though I am my folks' medical POA, and that worries me. She has told my father that she's not comfortable dealing with me so now she wont talk with me. Dad feels better but it's difficult to keep his BP, fluid levels and weight stable; he's not out of the woods. The CG tells dad that she can make him all better through diet and just having her around to do everything. Red flag much? I still handle all of my parents' medical concerns and ensure they take their meds each day.

Here's the problem. Dad knows I don't care for her; he's become very defensive of her. My siblings aren't any help because they haven't been my parents' protectors and unfortunately don't see dad as being vulnerable. Dad is planning on hiring her away from the agency at the first of the year, bringing her to Palm Desert with him and mom in February, etc. It's going too far, too fast. I'm assured by the agency that she's been through a criminal background check, but unless I see it, as well as reference checks, etc., I do not consider her properly vetted. As it is, she dresses like a slob in shorts, unshaven legs, scraggly hair, condescends to my parents, has bragged of all the restaurants she's owned and done her fair share of local name dropping... most, if not all, of the people were friends of my parents and are now dead. There are just a lot of red flags for me. Last, I cannot find her anywhere on the internet. I cannot verify any restaurants, property, prior addresses in any states she's lived in. I'm a pretty decent investigator, too.

Has anyone had experience with a caregiver about whom you've just had a feeling, one who instantly ingratiates herself, becomes indispensable; has full use of the vehicles, as much cash as she needs for grocery shopping, etc.? I already realize the MANY mistakes I've made in this hire and I've learned what to do and not do next but I have to fix this problem NOW, before it goes any further. If I can bring dad some bona fide examples of people similar to him who have been taken advantage of, it may help my argument.

Thank you so much.