Enforcement of will & Procedure thereof

A mother, Say Mrs Kaur , made a last & irrevocable will in Feb 2001. Will was for the property, she purchased some 30 years back. Will was in favour of her three sons., say A, B & C. Will was registered in Sub Registrar office Janakpuri Delhi on the date of will i.e in Feb 2001. In June 2001, A, B & C divided 3 floors of the property among themselves and transfered one floor each to A's wife, B's wife & C's wife by making following papers: - 1.GPA by A,B & C in favour of each one's wife. 2.Agreement to sale by A,B & C to each one's wife. 3.Sale Deed by A,B & C to one's wife. 4.Possession letter in favour of each one's wife. . etc. All above papers are notary attested. Mother died in April 2007. In Nov 2016 One wife, A's wife, Say Mrs A made a self registry, registered at Sub Registrar Office. by paying Govt's stamp duty. Here seller is Mrs A & Purchasr is Mrs A. Consideration amount is Approx 15 Lacs. Now Mrs A wants to sell her floor. My query is 1.Mrs A has clear marketable title to the property. ? 2. Enforcement of will before mother's death is valid? 3. Self Registry is legal. ? ... Please reply, advise in the matter. Thanks Yours faithfully Amol Ratan Singh