common area expenses in apartment complex with varied sized flats

If you are an aggrieved party, and if you want to penalize those who purchased only limited area they can afford, you can approach to Sub Registrar and can report this as a grievance, can call for General Body meeting, or can study the similar practices prevailing in such other societies.  There should be a standard and uniform practice, in an apartment only one senior citizen may be residing, but he has to share the maintenance equally with others that are having large families, children park etc.,.  

This is a matter where there can be difference of opinion. In Maharashtra there are Model Byelaws for Co-operative Housing Societies. Under the Model Byelaws salaries, power consumption etc are shared equally by all members irrespective of the area of the flat. On the other hand repairs, sinking fund etc are shared in proportion to the area of the flat. In fact members due to pay directly for actual repairs. There is a corpus called Repair Fund. Members contribute to the Repairs Fund in proportion to the area of the flat.    In Tamilnadu under the Tamilnadu Ownership Flats Act, 1997 all common expenses are to be shared in proportion to area of the flat only. In your case I do not know whether UP has any laws with regard to apartment complexes. I live in Maharashtra in a building having flats varying in areas from 350 to 800 sq.ft. I have 20 years of experience as Secretary of the Society. Now I am not a member of the Managing Committee. You find out whether UP has any laws in this regard. Is your society registered? If registered under which law of UP is it registered?  If it is a registered society, certainly they will have byelaws. What does the byelaws say about sharing of expenses?