How to change a name:
When a man or a woman comes to a Chabad House wanting to change his or her name, or wanting to add a name, how does one go about this?
Answer: Changing or adding a name is done by means of a Mi sheBerach during the Torah reading. If it involves a woman, a relative or friend should go up and do it for her.
The nusach (format of the blessing) is:

The name should be changed also in official documents such as I.D. card, passport, etc; When the name is changed and it becomes clear afterwards that the new name has not been in use, they should make sure not to change anything in the Ketubah. If both names are in use, it should be written in the margin of the Ketubah, that …… has come before witnesses and said that his name has changed and now it is ……………… If the new name has been in use for thirty days and the old one has been left aside, the couple should turn to a Rabbi who can write them a new Ketubah with the new name. (Mishpat HaKetuba Section 7, Chap. 68, Par. 61.) In the new Ketubah, instead of writing ‘De’eshtakach tauta’ (there has been a mistake), it should say: ‘shehosifu la al shma’, (that has been added on to her name).