Let us revisit the facts of the case on hand. Two independent apartments are constructed by a common developer/builder. Both have received OC for occupation. Both have independent associations duly registered for the maintenance of each of the apartment complexes. However both the associations are registered under KSR Act of 1960, and in this regard the Registrar of Co-op societies has issued notice for certain violations and the same is pending consideration.
In the above background, the developer is now claiming both the apartments are one and the same and the amenities provided in each of these are for the common use of all, which again is in contention and disputed by the respective owners before a civil court. The same is also pending consideration.
Now in the above scenarios,
1) Whether the land owners consent or not, sharing of amenities cannot be determined by a mere consent letter or agreement, it must be done with the consent of all stake holders, otherwise, the civil court only is competent to decide this issue.
2) If your legitimate rights are violated or breached, your legal remedy is to approach a competent civil court for a equitable solution.
3) Agreeing to share must be free and absolute, if it stems from fraud or misrepresentation it is against the principles of natural justice and thus can be questioned before a court of law.
4) Their act can be questioned before a competent civil court and alternatively those responsible if found guilty by a competent court can be prosecuted.
5) The act of providing access to both apartment owners to use the common amenities is based on a consent letter purportedly manufactured by the developer, this can be challenged by a writ petition before the High court of Karnataka and those violators will be punished by the Hon'ble court itself.
In depth perusal of the facts and documents would yeild proper solutions, hence consult an expert property consultant to pursue best options.