Can a residential property(house) be converted to commercial without a NOC from the neighborhood ?
The authorities will follow the procedures and if the rules permit then permission can be granted without NOC too.
And even if they did so without a NOC and in case they are paying property tax on a commercial scale (assumption) it will still be illegal to run dairy business which would create a nuisance right ?
Creating nuisance is always an offence.
And is a conversion possible when the house happens to be in a common passage Common for 3 houses ?
Or is it illegal to convert a house into a commercial property that could create a nuisance to the neighborhood ?
Which authority of the corporation should I be consulting in regards to problems like this ?
You can visit the corporation office and enquire the department related to your residential area and meet the concerned officer with an application venting out your grievances. Take an acknowledgment from him after submitting your application, wait for the actions to be initiated or a reply after which you can decide further course of action.