How to obtain Original documents from witnesses in Criminal cs

A parental property consisting of 24 shops has been disposed fraudulently by one of the brothers without authority from other heirs/brothers, in the capacity of Builder. A complaint on the basis of Zerox copies of the Sale/Purchase agreements signed by him resulted in an M case in the Magistrate Court in 2003 Under section 406, 420, 504, 506 r/w 34 of the IPC. Charge-sheet has been filed in 2004 without the support of Original documents (Sale/Purchase agreements), charges have been framed by the Court and the High Court has also ordered that the case should be decided in 6 months from Sept-2016. Now most of the witnesses, who were Shop owners and who have purchased these shops from my brother, the main accused, have sold their shops to a third party and a few have expired, after registration of the Charge Sheet in 2004 and hence their names don't appear in the Charge sheet. I being the original Complainant moved two applications for issuing of summons for production of original documents like sale/purchase agreements to witnesses who have purchased shops after the registration of the Charge sheet and to the heirs of witnesses who have expired. The applications were accepted and summons have been issued thrice but the witnesses don't appear in the Court. Only one witnesses has appeared during the last 4 dates and has submitted Court verified copies of the documents (Sale/Purchase agreement) but was not allowed to be examined by the PP since the accused, under the pretext that application for issuing summons for production of documents was allow but not for examination and cross. Hence i would request advice from legal experts in Criminal Law that: 1. How should i move further in this matter. 2. How should i gather evidence from witnesses to help my case. 3. In what manner and way should i approach or request my PP to move the case. 4. Since the forgery and fraud is in the form of documented evidence like sale agreements signed by my brother, is there any other way to nail him