As smarter people than me have already pointed out, your daughter is far too young to be making such a commitment. If you can, speak to a lawyer about this, stressing that this baptism is not like others but is a form of a loyalty oath to the WTB&TS and will make your minor daughter subject to JW "judicial processes." Have the lawyer prepare a letter to be delivered by registered mail to the PO informing them that any contracts your minor daughter makes are null and void and that you will sue the elders individually if your daughter is made to experience emotional distress as a result of this while she is a minor.
Even if your daughter REALLY wants this, it is still a bad idea. Let her get tattoos, drive a car, get married, join the Army, and do some boozing first. Then she can get baptized.
...and Jesus was 30 when he did it. Is your daughter as "mature" as 30-year-old Jesus was?
If it does happen, it would be excellent to have a video of the "happy occasion" with an interviewer saying "Today is (month) (day) (year), and we're here at (state place) with little (first name) (last name) who is preparing to take a VERY BIG STEP. (First name), tell us, how old are you? [allow answer in her own words] and tell us, (first name), what are you going to do today? [allow answer] Then get the names of the WT elders involved in this, and "interview" them, under the guise of "today is a very important day in (first name's) life. Will you offer a few comments for her to remember over the years ahead; some wise counsel that she will appreciate in the future?" The entire video can be done as a friendly, happy documentary - no need to be confrontational or offensive. But you'll have names dates, places and their own words which will indicate that they knew she was a minor.