Sister's claim in property

Hello, Myself & my spouse used to stay in US and had earned some money, which we transfered to our accounts in india. Some of the money was transfered to my parents accounts as well to ensure that they have some money to take care of any financial problems. My father used to invest this money in Bank FD's etc. We believed in him as he used to say all this belong to me. Later on we had mishap in the family and both my mother and father expired within short span of time, leaving no WILL and number of FD/investments build on our initial transfered money. Now my married sister, who could hardly could take care of my parents even in their hospitalization is asking for her share, We requested her that most of this money is from our money transfers and subsequent interetse accumulated on those inevestments. But she is not ready to see the money transaction records neither is she ready to sign the NOC docs easily. This owas our hard earned money and would be in justice to me or my spouse if someone woudl just want stake in this money which was basedd on our investements. What can be done in this regards. appreciate urgent response in this. Regards PSK