Returning of Kaveri water connection to BWSSB by Land owner of the apartment

I took a flat from builder, in Bangalore in May 18. The Apartment , which was constructed around 3 years back, has 8 flats and 4 flats are occupied by Son-in-laws of the Land owner. Land owner has died around 3 years back. His wife stays with one of the daughter's house in the apartment. While building, they say they have paid around 4.5Lakh to BWSSB for water connection and couldn't recover the amount from the builder. Now, they are threatening other 4 apartment owners(including me) who bought the flats directly from builder that, they will return the kaveri water connection if we don't pay the amount. our question is when builder was here around for 3 years, they didn't ask him and once he fled away by not completing some minor works , these son-in-laws are threatening us about the disconnecting water connection. Do you really think we need to pay this amount to Son-in-laws ? .. Without all the flat owner's permission, can they return to BWSSB ? will BWSSB accept their request ?. Also , For any other pending work, they don't want to put their share but they want us to do it. They are not willing to form the association but they want to maintain the apartment since anyway they are family members with majority. We are fedup about treating us like tenants from past 3 months. Can you please give us a clear cut solution ?