Passport re-issue and divorced without divorce decree

Hi, My brother is divorced and re-married. We did not approach any court to apply for divorce and there is no petition in the police station or the court with regards to this. With the mutual consent between him and his first wife, we got a Seperation Agreement signed by both the parties and closed the matter with the help of evidence signatures. Now when he is planning to apply for his passport Re-issue since he has got his first wife's name on his old passport, APO has asked him to get the divorce decree/notice and the marriage certificate of his second marriage. Divorce proceedings took place in around 2005 whereas re-marriage happened in 2011. We can manage to get the marriage certificate but not sure if we can get divorce decree now after so many years have gone. How to deal with this now and is there any alternate to divorce decree to get the passport re-issued? please advise.