Property from mother

A. We are 2 sisters and 4 brother for our father and mother. 1) Elder sister birth during 1938 ( Married during 1959).2) Elder Brother 1940, 3) Sister 1950 ( Married during 1979)4) Brother 1954,5) Brother 1958 6) Myself 1961 B. Father worked in a factory up to 1976. The factory provided house on "Hire and Purchase basis". Father expired during 1983. After long fight by residents of such houses the factory agreed to sell the property during the year 2000 and fixed the cost. Mother paid the cost and got registered the property in her name during 2000 ( all children's agreed and signed for the same). Mother made the will during 2006 to 2 sons ( above stated no 5 & 6 ) and signature of all children's (1 to 4) was also taken. The same was carried on stamp paper in the presence of notary ( signature and entry made in notary documents). C) Mother expired during 2007 at the age of 87 (appx) at the residence of brother mentioned at no. 2. Request for clarification required for below, a) Weather sisters/brothers or their children can claim property?. b) If the sisters/brothers claims the "will" is fake, what can be done. c) At present we ( no. 5 & 6) are staying in the same property as desired by mother.