1) you have stated that on your father in law death property was transferred in your mother in law name .was the consent of other legal heirs ie your husband / sister in law obtained . ?
2) if property was validly transferred your mother in law could execute gift deed in your sister in law name as she was absolute owner of property .
3)how did your husband also execute gift deed? once he had relinquished his rights in favour of you mother in law he could not execute gift deed .
4) you cannot contest the issue in court as you have no share in said property .
5) no case of cheating is maintainable