Sorry the info didn't show up on the other post.
It sounds like she may have a drug problem. When money continues to be needed, drugs of some sort are most often involved, and the lying around that issue is legend. I suggest not giving her cash. Talk to as many people as you can, and if you can bring everyone together to compare stories, do so. Not with the intention to gossip, but to gather facts. If it does seem like drugs, get education on the issue. AlAnon and Familiy Anonymous are international groups that meet weekly to help support family members of those struggling with drugs and alcohol. Talking to people in the same situation takes all the shame out of it and gives you great ideas on what to do. Once you feel grounded in information about her and her problems, you'll know when it's time to confront her.
On the other hand, if drugs are not involved, you may have a girl with Borderline Personality Disorder or Histrionic Personality Disorder. I'm going to give you some links on those.
For now, educate yourselves and get into contact with people online or locally who have similar issues. You don't need to reinvent the wheel, and you can use the support. She is not well, and needs you guys to be firm and honest with her. Make any help you offer her contingent on her seeing a counselor or psychiatrist.BPDCompulsive lying
this one has a good link on the right about confronting a compulsive liar.addictionHistrionic
This is such a painful experience for loved ones to go through. My heart goes out to you. Take it one step at a time right now. Gather the facts and find out what is really going on. Decide what help is available and what you're willing to do to get her the help she needs, and then set it before her and hold fast to your limits. This may be a long ride.
My best to you,