How can i obtain public records?

I agree, it sounds very bizarre! Since you are only your brothers sibling, she may not be taking you serious. I suggest you get your parents involved. Do they know your concerns? If they do and aren't doing anything, maybe you're overreacting? She could be playing games with you? Either way, she seems like she's a real winner! LOL But, if you are really concerned and your parents aren't, and you believe you are right, you can start at the court house; they contain records of everyone. Does she look like she's an illegal immigrant? Law enforcement would send her back to her country if you turn her in. You can try to Google her name; see what information you can find. If anything, previous addresses should come up. I don't know if you are being serious or not, but being that you're describing a person in the U.S. that doesn't work and lives off of everyone else, and is "disabled," I think you're telling the truth! LOL

I would hope that birth certificates wouldn't be available to people like you and, guess what? they aren't! Neither are social security records which are confidential and can only be released with the written consent of the person assigned the social security #. You want information get yourself a private detective and pay for it.