1) once deed of partition is made property ceases to be ancestral
2) since deed of family settlement is un stamped and not registered it is in admissible in evidence .
3) if it is a mere memorandum and records the settlement arrived at it is not required to be stamped and regd
4) the document cited by you has to be perused to advice
5) Each document has to be scrutinized on the basis of the wordings contained in the document to arrive at a conclusion whether the same requires being stamped and registered or otherwise.
6) Even if a family arrangement that required registration was not registered, it would operate as a complete estoppel against the parties who have taken advantage of the family arrangement
7) your mother in law and you have equal share in property B
8) you have 50%share in property B . your subsequent remarriage does not make any difference .
9) your mother in law can execute will in your daughter favour to bequeath her share in property B in kolkata