Question Summary:
How can I make a wasiyyah for my sister?

Question Detail:

 I am married and have three children, one son and two daughters. I work full time. I have a mentally handicapped sister that I am legal guardian appointed by state of Kentucky in US. I purchased a small apartment from my own income for her. That condominium is on my name but I want to give it to my sister after my death. How much right do I have on the house by the rules of Islam and can I make that decision for that property. I really need your help in this matter. 

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
If you intend giving the condominium to your sister, we advise you to do so in your in lifetime.
If you are survived by your husband, son and daughter, your sister will not be your heir. Accordingly, you can make a wasiyyah (bequest) of one-third of your estate after burial expenses and debts. The challenge would be if the house will be within one-third of your estate or not. Furthermore, you may now know who your heirs are but the future is best known to Allah. Your sister could be an heir and as such, she will disqualify for the bequest.[1] We therefore advise you to gift the condominium to your sister in your lifetime.
 
And Allah Ta’āla Knows Best
Fahad Abdul Wahab
Student Darul Iftaa
USA
Checked and Approved by,
Mufti Ebrahim Desai                                                                                                                                                                                                                
www.Daruliftaa.net