Registration of Family Settlement

My grandfather constructed his house in 1940 in Lucknow and left it by will to my father. My father did not make a will before his death. My father had three sons. After fathers death the three children and mother had a amicable discussion and made a Notorised family settlement in which, following division was agreed Son[deleted] sqft (constructed area nil ); Son [deleted] sft (constructed area1000sft ) ; Son[deleted] sft (constructed area 1000 sft ) Mother agreed not to have any share . The Khasra has been changed to the respective owners in the Municipalty. We understand this agreement should be registered with the sub registrar so that each person can become individual owner of their portion of the property independently, and this is the proper legal procedure. Questions: 1 Is my understanding correct ? Are there any other aspects/issues/problems ? 2 What will the total expenses ( stamp duty, regn fees etc ) for registration of the family settelment ? what is the procedure and time needed. 3 Are there any other formalities necessary before each becomes individual owner ? 4 In case say only one son wants to sell , will it be necessary for the Mother and the other sons to be “consentors” in sale agreement ?