Registration without legal title

A residential building was constructed by a Developer who had the rights to construct via POA of the owner of the Plot. It is a CIDCO developed Plot and assumed to be Legal in status. After completion of the construction but before getting OC/CC the Building remained vacant / in dispute with the purchasers on the point of obtaining OC/CC. In the meanwhile a third party Developer has "illegally" sold 15 flats by using his own Agreements of Sale which is different from the Original Developer. On getting 12 such purchasers he has managed to Register the Society as a Hsg Society and now there are two different sets of Purchasers of the Flats in the Building. The Purchasers who have bought from the 2nd Developer are refusing to show/ part with a copy of their Agreement for us to verify how he obtained the Legal Title (if at all). He has managed to coerce a few of the original purchasers to sell off their titles and thus is retaining the copies of the earlier registered Agreements. Since majority of the members have now occupied the Building without OC/CC and with the 2nd Developers Agreements in a Registered Society the original members are facing loss of their flats for which money has been paid to Developer No 1 who constructed the Building but took no interest thereafter citing that he has completed his part. This property lies in the Thane District and I would appreciate if any of you learned Advocates have dealt with such matters which would probably fall under Property matters and also Criminal once we are able to lay our hands on a copy of the 2nd Developer's Agreement and ascertain how he is claiming Title and Selling rights. Second how was he able to get registered a Housing Society when one of the Documents required is a Title Search and Certification of the Property Rights in his name. Just that there is no misunderstanding I am clarifying that if Original Developer is ABC (Sole Proprietor) and Second Developer is XYZ (Sole Proprietor) ABC has confirmed he has not passed on any POA or rights to XYZ, he is is not related to XYZ and he is willing to take any legal action along with the Original Purchasers against XYZ but (in our findings till now) is not willing to do so on his own, I am also aware that we have recourse to Consumers' Forum (against Dev 1), etc but we would like to first proceed against Developer 2 to get back the property and then against Developer 1 for Legal Possession with OC/CC.