Little back story…former wife and I divorced back in 2005. We have a son together.
Both of us (ex and myself) have since remarried…other people… 
I am still married to my “new wife”…but the ex’s “new” marriage only lasted a year (the guy ran into the same issues I did).
When my exwife remarried, she changed her name to (first-maiden-new husband’s last name). She has been divorced about a year from him at this point.
I get an email this morning that states that she has changed her name back to “her son’s name”…which now reads as (first-maiden-my last name). So now she is back to using my last name…the same name she used when we were married. Kind of bothers me in that she is somewhat (to put it nicely) delusional that Im coming back to her…and she would welcome me back…and that my child with new wife “is supposed to be her baby”…and we live in a small town.
Concern/Question:
I wasnt aware that someone could change their name back to a “former married name”. If you can, what do you have to show at Social Security? This just seems wrong to me…I see there being issues down the road because of this…banking, social security, professional contacts…etc…
and it just seems crazy to me.
So, is changing her name to a former married name “legal”?
thanks for any insight.
ididit34