right to ex husband last name

What is the name of your state? Ca
My Questions is my husband has an ex-wife she is caring his last name! the problem is that she was married before him then got married twice again after him, and still went back to his last name. She has two kids with two different last name. So after 4th divorce she went back to her second husband last name. Which is who I'm married too.
Can she do that. I know she can have any name that she wants, but worries me is that she has all info on us. We know someone has tried to get credit cards under that name so what should I do ??????

You can't do anything. She's allowed to use any name she likes, as long as it's not for fraudulant purposes.

Yes she's entitled to use that name. Unless she's committing a crime against you (i.e idenity theft) there is nothing you can do and it doesn't relate to her legal name anyways.

WTF difference does it make WHAT she calls herself? Lots of people share the same last name with others, and many have no relationship to each other at all. I have no doubt there are others out there that also have the same last name.