What should you do if you expect elder financial and verbal abuse?

I agree with pamstegma.

If this 78 year old was my mom or dad what i would consider doing is & involve them if they are willing & competent enough to go along with it. But the 78 yr old can't help it if they "get a letter" in the mail. If you have to talk to a adult protective service worker & explain to them what is going on & the 78 year olds concern. If ANY WAY they can most likely they will be the "bad guy" & SEND THEM A LETTER. The letter can say we have concern & feel you need a POA or payee etc someone who is over their finances NOW. That person can be you. Tell your sisters whats what & if they want to get mad then get mad & to grow up. MOM OR DAD COMES FIRST.

So do you have your POA for your mom in place? Does your mom have dementia or another illness that would affect her decision making capabilities? Maybe you need to discuss with your mom that she is an enabler and needs to be protected from this financial and mental elder abuse. My mom resigned as Trustee and though it took a year to clean up legal matters, I now have her accounts safeguarded from my brother. My mom would rather do without and give to my brother who doesn't work. He knows the exact words to get her to volunteer to give him money so he can say he didn't ask for it. all I can say is to get your legal ducks in a row and act as if you were the bank not just a daughter. She will need what she has to take care of herself.

The 'suicide' talk is likely just that. People who constantly threaten it rarely if ever go through with it. Mother used that threat my entire life until I told her to go ahead and please not leave us a mess to clean up.
Sounds like you need a family chat NOW and clear this up. And if that doesn't help...walk away. (Run off?? I'm 60 and the furthest I can "run" would be the local Marriott. That's a ploy if ever I heard one.)

How do you fit into this family scenario? Sit down with the other two and talk about issues, get them out in the open. Life is not fair, but if you are unwilling to stand up for yourself, then you will be taken advantage of and the sibling who either talks about suicide is mentally ill and needs professional help. People who talk about suicide enough might actually do it. If she "runs off", then the 78 yr. old will be rid of her. No one can delegate what is or is not "correct" behavior. If your siblings are living together, and the 78 yr. old is complaining about the 60 yr. old, then that is their business. Try to find some compromise, or stay out of their business.

1877-597-8871
Kentucky Dept of Community based service
This is financial abuse
Work with KY dept to stop this and also get help filor your dad

They are what you call "co-dependent". You can't fix that. Walk away.