If a will is executed at Chennai, or in respect of property situated in Chennai and executed elsewhere, it must be probated. Once the will is probated, both your sister and you can deal with the respective entitlements. A family settlement can be entered into, between the family members, if there are any disputes between them, regarding their entitlements. Such a family arrangement can be either oral or through a document, which has to be registered. You may use the remedy that you find applicable to the facts of your case.