Is it elder abuse when sibling is blackmailing parent?

I do not see blackmail here. Blackmail is the action, treated as a criminal offense, of demanding money from a person in return for not revealing compromising or injurious information about that person.

Yes this is financial elder abuse. Clear the house completely out. Don't leave a stick of furniture in it. In the mean time, contact the area agency on aging in your area to report what is happening. I would be afraid if he doesn't get his way, he may step it up a notch. Don't give him any money. The pipe line will never be shut off. He will come up with something else later when he needs money again. The money from the sale of her house is for her care. Period. It really burns me when I hear of someone taking advantage of an elderly person. How low can a person sink?

Due to the state law an attorney can not evict him because he is not considered a tenant in the legal sense due to the fact that he never paid rent nor had a lease agreement (if he had then he could be evicted). I talked to many different attorney and they all told me the same thing. He is a family member and has rights. I wish I could pursue an eviction notice.

I wanted to know if this was a form of elder abuse blackmailing my Mom by demanding money from her or else he won't move out. He is causing her stress by doing what he is doing.

Thanks.

Now you ramp it up a step. If you are close to closing, you pursue an immediate eviction notice. The lawyer handling your closing can help with this. If he is threatening you or mom, you pursue an Order of Protection.