Legal Question in Family Law in California

You can legally use any name you want as long as it's not intended to deceive or defraud. My ex had been married before me and kept her husband's name when they divorced. She developed an excellent career and professional reputation under that name, but wanted to take my name when we married, so our legal last name would be the same for both of us and our children. So once we married she went by my last name for formal legal purposes but continued to go by her first husband's last name professionally. All perfectly legal.