Ancestral property - BMC notice of depalidated building

We have our ancestral property in Mumbai which is occupied by our cousins and their parents. It is quite an old building with tenants (pagdi system) for quite a number of years on the ground floor as well as some on the first floor, it is a 2 floor building. The building is in dilapidated condition with a BMC notice clearly stating the condition of the building is dilapidated. Our cousin says that they are awaiting the building to collapse so that none of the tenants will have any right to property and all the property will be shared in our family, is this true ?? The tenants on the other hand want their share in the property, most of them are commercial properties and they want commercial shops after redevelopment. But my cousin wants to redevelop on his own and says that he will give the tenants their shares When we went to meet our cousin and did mention to see the papers of the property he denied by saying that he does not have them with him…they are with his lawyers etc…We have a doubt in his intention too that he wants a bigger pie in the property as he did not reveal a single document of the said property. He also asked us that he would require an NOC from all the stakeholders whenever he will start to redevelop the property and he will give a certain amount at the beginning of the construction of the property to all of us for the NOC but never divulged the exact amount each stakeholder will be getting. My questions are 2 First, if the building collapses who will be the owner of the property ?? and if the tenants will cease the ownership in such property. Second, which papers do we need to ask him to show to us of the property and whether we need to make an MOU as per the payment and the details of the building prior to the start of the redevelopment of the building by him between us and my cousin. Awaiting an early reply from you all.