What is the legal procedure

My grand father has 5 Daughter and 2 son, After marriage of 4 girls and 2 sons grandfather died in 1987 , youngest one girl not married and live together mother. year 1990 2 sons are agreed and divided property in to 3 parts, 1 each of 2 sons and 1 for unmarried sister and mother. not given any shares to that 4 married girls. this partition is done in front of village people written in white paper, important is, it is not registered. 2 sons and their mother no more now. son of the 2nd son sold his fathers part to third party. and the 5th unmarried girl want to sell her part. now the 4 married girls asking share for them. as 2nd sons parts all are sold by his son. Q1. UNREGISTERD white paper writtned settlement is it LEAGALY ACCEPTABLE or VALID. Q2. 4 married girls do they have rights to ask share now . To retain my fathers part with me, i am ok to go with some settlement with 4 girls. Q3. what is the procedure to collect settlement amount or shere from the 1st son family. Q4. can i buy the property from the 5th girl.