I know I'm a bit late entering the discussion, but that never stops me. The impressions I got from what I have seen are that the parents didn't know that she had internet access or the phone. I know they had some experience with internet usage in the past because one of the relatives mentioned that they had talked to the kids on Skype until fairly recently. If the accounts were opened in December (I think I read that here), she may not have realized she could use the Internet with the phone before then. It seems like she kept the phone a secret from the parents because she always seemed to be rather quiet and behind a closed door when she was using it.
I think she may have taken one of DT or LT's old phones to use for pictures and videos, and just started posting them online when she somehow realized that she could get access through wifi with a deactivated phone. The most positive thing I got from what I managed to see is that her songs probably helped her maintain the strength to carry out her plan. It seems like she was working out a lot of her sorrow, frustrations, anger, etc. by writing and singing songs about them. That seems like one of the healthiest things she could do living in the circumstances she was. MOO