Is Diovrcee entitled to family pension.

Hello Sir, My sister married a person who was working in Unani dispensary under temporary roles and a son was born out of the wed lock and problems started and my sister opted for Khula due to undue pressure from her husband and the Khula was executed in a stamp paper ( Not by Jamaat from Masjid as per sharia law), where in she has made declaration that she is going to forfeit all the rights form the husband including uprising of the son and she remained without further marriage.The so called brother in law married another women(Second Marriage) while working under temporary roles within a year and subsequently during period of years he got permanent post and there are no children out of second wedlock. The so called brother in law passed away while in service and my niece being only child is entitled for compassionate job as the second wife is critically ill and she is 54 yrs now. I need to know whether my sister is entitled for at least 50% of family pension and pensionary benefits...please advise, if there are any citations or judgements available, as the deceased divorced wife is entitled for family pension. Thanks & Warm regards, Asif