No. Your friend if she is a US citizen (USC) can petition for her parents as Immediate Relatives (IR). There is no derivative beneficiaries; meaning the parents cannot bring anyone else with them to the US. Your friend would have to petition for her sister in the F4 category which takes over 20 years from the Philippines.
The quickest way for her sister to come over and still be under the care of a parent would be to have one parent immigrate first, petition for the child as an F2, become a US citizen, and convert the application to an IR. The second parent's petition could be filed around the time of converting the child LPR-F2 app to a USC-IR app.
Best of luck to your friend.
P.S. If your friend is a LPR (green card holder), she cannot petition for either her parents or her sister until she becomes a USC.
QUOTE(Ash_Cypress9507 @ Jul 24 2008, 07:41 PM)

Hi everyone...I would like to ask a question for my friend and would appreciate any helpful infos.
She has an adopted sister, which is 6 years old now and whom she took care since infancy like her own. Based from research and various experience of others that length of process on petitioning parents is faster compared to petitioning their siblings. Since her little sister is under age, can she petition them together at the SAME TIME? She is concern of leaving the poor kid alone by herself and for her own peace of mind as well that she is well taken cared of...Any similar experience or helpful infos that i can relay to her would be greatly appreciated...T H A N K Y O U!!!