Hiba Inheritance Islamic Law

This is regarding the inheritance of the property. Kindly give us the legal opinion on this. This is pertaining to the Islamic Sharia on inheritance. My grandfather had a property consisting of house and a rented shop which he received from my great grandfather. My grandfather had 1 son(my father), 3 daughters. My father died in the year 1999, and shortly after his death, my aunts forced my grandfather to do the HIBA of the said properties and within six months after my father's demise, the property was transferred against HIBA of Islamic Sharia wherein He (grandfather) in his life did hiba (gift) and registered in the registrar office and gave 4 equal shares in house (3 to his daughters and 1 share to his 2 grandson ( elder grandson being myself), and 1 granddaughter), younger grandson and grand daughter were both minors at that time and my mother was made guardian, and the division of property made in the 5:5:5:2:2:1 ratio. Am one of the grandson, my brother, my sister, and my mom were all living in the same house since my father time ( residing in the said house for the past 30 years. Meanwhile, my aunt (my father's elder sister passed away in the year 2005), and then now last year in 2014, my grandfather passed away, but the said property is not enjoyed by none of them. The rented shop is given to only 2 daughters (1 alive, 1 dead). All are registered as HIBA at the registrar office. I would like to know whether the HIBA can be cancelled or we as a grandson are entitled in our grandfather property after his death. We were kids when this things were done citing my father's demise, they never wanted it to be inherited to us and only on moral grounds gave us 1/4th of the share in house. Kindly suggest a legal opinion on this.