How to proceed when witnesses in a case turn hostile?

My brother sold 20 shops owned by my father without legal authority in 2003. I filed a criminal case against him under sections 420, 506, 465, 467, 468, and 471 - U/s 156/3 in 2007. The investigating officer made my brother and his wife (shop purchaser) the accused but made the remaining shop purchasers witnesses, even though they purchased shops from my brother illegally and should have been named as accused. The cross-examination of PW1 is in progress. The witnesses are now playing politics and are against me. The police refuses to entertain my fresh complaint to register offences against the witnesses. My app says it is too late at this stage to make the witnesses accused. Please advise how I should proceed.