Uncle & his son forcebly not allowing to construct our portion

Hi, >This property is in the name of my Grandma & before her death she did not make any Will. >My father has 4 sisters (who all are married & well settled) & one younger brother (married) >Our property is rectangle shaped & mutually divided lengthwise. >My uncle has built their portion completely & now not allowing us to build our portion. >What they want is to use common entrance through our part of the land & also want to park their vehicle at our place. >Because of which we are not able to build staircase & unable to capture the roof which is common & our portion is empty. >Unfortunately my all aunts support my uncle because of which my parents are forced to spend their life in a single room. >Last but not the least my uncle & his family (specially his Son) are extreme abusive & do not think twice to become violent on my old aged parents. Please suggest what shall I do to help my parents as elder daughter.As per my aunts as my parents doesn't have Son so they do not need much space to live their life. Please advise what can I do to support my parents in this crisis as they are feeling very helpless. Thanks, Mou