Paying Zakat to parents, brothers and sisters

I knew that it is not permissible to pay Zakat al mal for parents. But, in my case my parents have my youngs "2 sisters and a brother", all students in the University. Also, I have other 2 married sisters and all of them are poor. Can I pay Zakat el mal to my brother and sisters who are living with my parents and to the other married sisters?
Note: My parents income is so small that it just only cover their living alone.

Praise be to Allah, the Lord of the Worlds; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
Paying Zakat to brothers or sisters is lawful according to the prevailing opinion of the Muslim scholars, especially if they are needy or poor. It is even desirable according to the following Hadith. The Prophet said: "Giving alms (Zakat and others) to needy people is rewarded as alms only but giving them to a needy relative is rewarded both as alms and as a treatment that strengthens kinship". [Al Nasai..]
So, if you have needy brothers or sisters who do not have anyone to care for them (a son, a husband or whose father is poor himself) there is no harm in your giving them your Zakah. It is even desirable as mentioned earlier. They are eligible to receive Zakah even though the husband or father is alive as long as they are poor and cannot spend on them.
Allah knows best.