Can a father give his entire property to only one child leaving the other ones

My grandfather has 6 sons and 2 daughters. The eldest one is his daughter who has seprated from her husband and has 2 kids, and staying with my grandfather,,then he has 6 sons and then the youngest daugter she is unmaarried and use to stay with my grandmother and grandfather..we all stay in same building but on different floor..all 4 eldest sons have started business on their own ..my grandmother has expired 6 years backk..and my ggrandfather expired on decmber 2016, he use to stay with my youngest uncle 's family (chacha) and along with them my youngest aunt (bua) . my grandfather owns 2 shops and 2 house.many years back she gave one house to my eldest aunt I don't have any information regarding it, whether my father has relinquished his right signed any document or not (NOC)....rite now that is not my concern I am concerned about the other house and 2 shops, till the time grandfather was alive we never claimed rite on these shops..both the shops are being run by my 2 younger uncles...one each. now since grandfather has expired we want to claim our rite and ask for partition. Question 1) what if my grandfather when he was alive at that time only transferred the shops and house to my uncle and aunt...?can my father file a suit against it as even he has equal right in the property? Question 2) what if he had not transferred the property but made a will that after the death the house and shops should be given to her daughter???? how can we now that it was done by her will and he wasn't forced for it?can we challenge the will as my father has not got the rite in property and he is also the legal heir Question3) what if my grandfather neither transferred his property nor made his will??? can we ask for our share in the property as we have a legal right to it.