Daughter's right in self acquired property

My parents started from scratch, they had nothing. They worked really hard to bring us up 5 siblings, educate us. however they are always inclined to my only brother. As girls we had to sacrifice a lot so that my brother can have better things. one of the plot was sold to pay his fees. Now the only house we have, my parents want to give him, with absolutely nothing for us. The point is, we also suffered a lot during our growing up days, since every decision was linked to my brother's future. This I feel is not right and a discrimination towards girls. My dad passed away without writing a Will, but my mom wants to do the same thing. Now, my mom and brother want to mortgage our house to deal with their loans. And want all the daughters to sign a document, all my other sisters signed. But somehow I am not convinced to sign, since I feel they will sell the property without our knowledge and spend as they want. But this house is sweat and blood of my parents and all our hardships. Is it right for me not to sign, and in case I do not have any legal right on self acquired property why should I sign in first place?