G4 Visa Help

Hey,
So my friend was here on a G1 visa under one of her parents (both parents are diplomats, so they each have a visa) that parent left and she stayed with the other parent, that has a G4 visa, (but i guess has been without a visa for some time now because she never switched over to her other parents)
She is older than 18 and unmarried and lives at home, that still counts as being a dependent correct?
Also how would she go about applying to be under the other parents visa?
Please let me know ASAP!
Thanks soo much!

Dare I ask, why are you asking this instead of her? And why can't she get assistance through the embassy?

1. I'm asking instead of her because shes soo frustrated with the situation, so I offered to help.
2. We've tried calling the embassy but no one was able to help us, and we kept getting different answers, which totally confused us.
We were told initially that she does not count as a dependent, then someone else said she did because the rules are different for Visas then for Immigration and then we were told to call the department of homeland security, because they are the branch that deals with visas, but whenever we called them they bounced it back to the former INS and we tried calling the US embassy in her country, Ghana, but the calls kept getting dropped or they didn't know what we were talking about. (We also tried e-mailing them but they never responded)
So at this point we feel like we've exhausted all the options we can think of. If you have any advice it would be greatly appreciated.
Thnxs!!