Heidi, who starred on 'AGT' as one of the judges, took the final legal step today in LA County Court as a judge legally ordered her name be changed to Heidi Kaulitz. The judge issued the order without Klum having to appear in court, and instead issuing a ruling to legally establish her new name.
In the documents, she simply cited "marriage" as the reason for the name change. Of course, this is a very common occurrence when people get married, but in the case of someone with arguably one of the most famous names in the world, it is not a guarantee.
In many celebrity cases, such as Klum's, celebrities will keep their famous name so when they sign contracts or sign any legal document they can sign with the name that carries weight.