Residential/commercial usage

We are builders running the business of construction of apartment and villas. A property was purchased by us for construction of apartment in cochin city. During the project progress ,an adjacent property was also purchased by us for the same purpose and a single permit for two tower was obtained for construction. These properties are lying as a single unit with a common entrance. For constructing the apartment the undivided shares in these properties were sold out seperatly for 1st and 2nd tower. Out of the undivided shares in 1st tower 20000/90000 is in our ownership itself. Even if the building permit had not provided for commercial buildings in the 1st tower,a 3500 sq.ft office was functioning in the 1st tower and the same was regularized by the muncipality, upon completion of the building and seperate building nos was issued by the muncipality for the office space also and till now they are collecting property taxes and shops and establishment licenses were also issued. These office was functioning from 2010 onwards. Now the association of the 1st tower have objected the running of the office and claiming the property could only be used for the residential purpose as the permit obtained is the residential .and they also denying the access to the 2nd tower as the undivided share of two tower are sold out seperatly. They have instituted legal proceedings in the civil court seeking injunction with out joining muncipality and 2nd tower owners as parties to it?? Kindly be pleased to clarify the following?? 1. Whether the proceeding is maintainable in a civil court ? a. non-joinder of necessary parties? b.Jurisdiction ? civil court /tribunal? c. any other ground to counter? 2. What are our rights over the issue and defences to be taken in this regard? 3. Suggestions as to evidences to be submitted for proving our rights??