Ancestral property bequeathed to my mother via her grand mother

Dear Sir/Madam: I shall appreciate knowing if I as a son were allowed a share in my mother's ancestral property. The fact is stated here below: My maternal great grandfather self-acquired property and later bequeathed/willed it to my maternal great grandmother and later to his only child, his daughter (my maternal grandmother), that is, either of the survivors, and thereafter, the property to be divided by the children of my maternal grandmother as stated above, my maternal grandmother had 6 children and one of them is my mother. Unfortunately, my maternal grandmother passed away before my maternal great grandmother. Later, when my maternal great grandmother passed away the property automatically was bequeathed to her 6 grandchildren as stated above. My mother acquired her share of the property, which is 1/6th of the total share. My mother, in turn, willed her 1/6th total share of the ancestral property (mentioned above) only to my sister and excluding the rest of us from the will. Can this be legally done? when the property in question was never self-acquired by either my maternal grandmother nor my maternal great grandmother, it was simply willed by my maternal great grandfather, who had self-acquired the said property. Please advise. Thank you for your kind gesture.