Why should we?

Respected experts, My ex wife is still occupying a part of my house built by my late father inspite of divorce up held by Hon High Court 2 months back. The petition was filed by me on Cruelty ground. Now after the divorce she is filing several false cases still posing as my wife. She also filed a false FIR against my sister. Police booked her under IPC 107. After 2 sitting with the ACP he is insisting my sister to execute a bond. My questions are, (1) She is not my wife anymore. She showed her self as my wife in her complaint. (2) She is a trespasser (3) Occupying and living illegally in my house. (4) Filing false cases police are aware of. Inspite of all these facts why should my sister execute a bond ? Can my sister refuse on the above grounds ? Kindly advise