Father gifted propety to his only son depriving 3 sister.

Q 1. Father,mother,1 son & 3 daughter(all are hindu), father gifted his house property(which recd.through partition deed from grandfather)to his only son depriving 3 daughter sometime 2 years back,which daughter does not know. Father expired in February 2015.Now son executed a sell contract of father's house property of 20 cottas without disclosing anything to sister's. Is the sell legally valid?Are the 3 sister can get or demand equal part(value) share,i.e.equal 5 part in total ?Is it legally justified till now?Even we do not know wheather brother has a gift deed or sell deed with or without registration. brother was an employee as land & land revenue officer in West Bengal govt. & retired as a Deputy Magistrate from Krishna nagar under D.M.Krishna Nagar at West Bengal. Q 2. Same family widow Mother alive.Only son sold one property belonged to mother,trying to sell another property of 10 bigha's land (mother). No share given. Is the sell legally valid? Are the 3 sister can get or demand equal part(value) share,i.e.equal 5 part in total ? How Please let us know in detail about both question.