Grand daughters rights in geand fathers property

My Grandfather (GF) has self acquired properties from his maternal aunt by way of settlement deed with wordings like "putra-poutra". GF has 3 sons and 1 daughter i.e SON1, SON2, SON3 and DAU1 I am grand-daughter of GF and daughter of SON3. Both SON1 and SON2 have sons. Before GF death, GF left a will bequeathing his properties to sons only with SON1 being the executor. The will's geniuness has been chanllenged by DAU1 and has been pending for years. SON1 and SON2 are not cooperating with my father (SON3) and are not giving the details of the case. They have even delayed filing for probate. We suspect them to have malicious intentions to get the properties transferred to their sons( owing to putra poutra clauses in GFs property docs). My father (SON3) wants to ensure that his rightful share gets transfered to me. If he gets his share during his lifetime, he will transfer the property to me. But is worried if he doesnt get his share during his lifetime as he is a senior citizen My questions are 1. Assumming the case wins and my father SON3 is entitled to 1/3rd share. If my father ( SON3 ) dies before the case ends, will my fathers share be given to SON1 and SON2? or Will I get my fathers share ? 2. How can my father secure his share (whether 1/3rd or 1/4th) to me? Should a will or settlement deed or anything be done during his lifetime, so that in the event of his death (before acquiring his share) he can pass it down to me .