Redevelopement

Sir, Our society entered into redevelopment of society bldg with the first developer who inturn appointed sub-developer. They both have failed to deliver. Now a 3rd developer has approached the society to complete the project through the 1st and 2nd. An agreement btw the society and 3rd developer needs to be signed. 3rd developer has agreed to take care of interest of the 1st and 2nd developers. However, the 3rd developer has refused to make the 1st and 2nd developers as the confirming parties to the new agreement with the society. How to make sure that there will not be nuisance for the society? What sort of further Agreement/MOU needs to be entered into? And with whom?