Whether it is a stridhan or joint property? (Civil Law)

In the year 1948 Residential house property was purchased jointly in the name of my grandmother (father's mother) and my father , My father was minor during the purchase of the property. later my father passed away in 1991, my mother became joint owner with my grandmother, In 2004 my grandmother (my grand mother was not in possession) sold the half portion of the undivided joint property to stranger (not belongs my Hindu family), where I and my mother didn't put signatures and didn't participate in the sale transaction and also there was no partition deed made between my mother/father and grand mother. stranger filed suite for partition on 2006, In between my grand mother has passed away.we filed an application based on "Section 4(1) in The Partition Act, 1893. based on this Honble Court has ordered in preliminary decree saying that My mother can purchase the portion of property, which was sold to stranger at current market value.Now the strager purchaser has put an appeal in district court and his contention is property purchased in 1948 is a stridhan property (section 14 of hindu successation act). hence its not a joint property Section 4(1) in The Partition Act, 1893 will not attract. So need you are expertise here.. Though in the 1948 sale deed they have clearly mentioned that my grandmother name and my father name (Minor) are the buyers. and there is not even single sentence mentioned about what is the source of money. does it still attract as stridhan property?