1. There are few loopholes in your query,
2. After the demise of your father in law, intestate, the property was inherited by your mother in law, husband and sister in law. How was it transferred in the name of your mother in law? Was there any gift deed registered by your husband and sister in law gifting their share of the property in the name of your mother in law? If yes, then your mother in law was the sole owner of the said nproperty and she alone is authorised to register a gift deed in favour of your sister in law. How has your husband executed the said gift deed alongwith your mother in law?
3. However, be whatever may, you have no share on the said property of your father in law in any way,
4. You can file no case against your sister in law, leave aside cheating case, since you have no locus standi in the matter during the lifetime of your husband.