Clarification on share in father's property after his death

My father and his 2 brothers purchased a land and build a 3 floor building for each brother. after my mother dead my father married again and had one son and one daughter. we are 3 siblings. after my father death my step mother married again. and now my uncle is not providing me with the property papers and creating problems. and does my step mother get a share of the property because she married again after my father death or only me and my step siblings are the only heir. and as my step siblings moved from india and are not interested in the property can i alone deal with my uncles legally for the issues regarding sale of the property. TIA