Inherited Property from my grandfather to my father and to me & my siblings after my father's death

We are claimants of inherited property from my grandfather to my father in Delhi and Punjab. My father died three years ago. One of my uncle is not agreeing to do a partition or a sale and all other family members have tried to talk to him in all best possible ways but he is not willing to do a partition because of an unknown reason and he holds all the original documents and we do not have any original documents and we have only incomplete copy documents. We also feel that he may not give any other member of family the shares/rights in this properties of my grandfather which is located in two different locations in New Delhi. We also feel that he may sell the property without sharing any benefit to any other family members. My father also had a property that he purchased and my mother, me and my siblings become the legal heirs of this property after his death. Me and my siblings would like to make a relinquishment deed in my mother's name on all the properties My questions are as follows: 1) How can we claim our right or division in the joint property of my grandfather that is in two different locations in New Delhi? 2) Can my uncle sell the properties of my grandfather alone and enjoy all the monitory benefits ? 3) Can my uncle use the properties of my grandfather alone ? 2) In case we execute the Relinquishment deed in my mother's name for all the properties, my mother will enjoy all benefits and do we all siblings gets equal rights on all the properties after my mother? What should be taken care and documented with authorities to have all transactions smooth and without any confusions at a later stage. Thank you Ms. Rose