Then your story her BS. If she was only three when she snuck in, and she's been paying a mortgage for 15 years, she must have come before 1986. That means she was eligible for the last amnesty and already has a green card. If she doesn't, she's lying to you about something.
Yep, she came in in the early 70's I believe, was too young to understand the ramifications of the '86 Reagan amesty and didn't take advantage of it.
Oh well...we just kick her back to Mexico...it's easy. We'll make her life a living hell and she'll go back on her own...LOL