Child Custody Order from High court

Dear Sir I am Idris (35) and have recently married to Almas (40). This is my first marriage while its 2nd for Almas. I have a Step son Arbaaz (15) from Almas first marriage. Almas earlier married in 1999 and she got divorced in 2005 from her husband because of their regular misunderstandings. The dispute was referred to local muslim jamath (Salem, Tamilnadu) and with each others consent they divorced. Since the birth of Arbaaz he is with Almas and each and every thing of his is taken care by Almas. Almas is higher secondary Science teacher in a reputed school. Almas has Deed of Divorce with her and custody letter of Arbaaz issued by Office of Chief Kazi to the Government of Tamil Nadu, Chennai. Recently we have applied for Arbaaz passport and we got appointment from Coimbatore passport office. We carried deed of divorce and custody letter issued by Kazi but the passport application was rejected saying that the custody order of the child should have been issued by High court in order to process the passport. Arbaaz's biological father had not been bothered to take care of him nor tried to meet him in all these long years and even we are unaware of his where about since years as he was employed in abroad earlier. In such circumstance could you kindly advise us on procedure of how to get High court order of Arbaaz's custody to Almas, to proceed with his passport application and for future legal custody authority of Arbaaz. Should you require further information from me in order to better guide me please do mail me.