If she didn't buy the LLC, what gives you the authority to change its sole member?  That's a matter involving state law and just because she doesn't want to hire a lawyer doesn't mean you should help her botch things up even worse.

Get her a new EIN, now, and file payroll and income tax returns with it from now on.  You've already filed some quarterlies with the previous owner's number?  Well, that was a serious mistake.  I'm sure by this time next year you will have it sorted out.