Passage , staircase , lifts ,terrace , car parking area , land form part of common areas 

Under Real Estate (Regulation and Development) Act, 2016 Section 2 (n) "common areas" mean—

(i) the entire land for the real estate project or where the project is developed in phases and registration under this Act is sought for a phase, the entire land for that phase;

(ii) the stair cases, lifts, staircase and lift lobbies, fir escapes, and common entrances and exits of buildings;

(iii) the common basements, terraces, parks, play areas, open parking areas and common storage spaces;

(iv) the premises for the lodging of persons employed for the management of the property including accommodation for watch and ward staffs or for the lodging of community service personnel; (v) installations of central services such as electricity, gas, water and sanitation, air-conditioning and incinerating, system for water conservation and renewable energy;

(vi) the water tanks, sumps, motors, fans, compressors, ducts and all apparatus connected with installations for common use;

(vii) all community and commercial facilities as provided in the real estate project;

(viii) all other portion of the project necessary or convenient for its maintenance, safety, etc., and in common use;

You say you are living in a joint property as a co-owner with an undivided share, where each lives in his own house and there are some open areas. From the arrangement you have described, except the built area (meaning dwelling houses for co-owners), all other areas, including the car-parks, are to be considered as common areas meant for use and enjoyment of all the owners of the joint property.

- In a joint property , the common areas may be hallways, sidewalks, parking lots , staircases , lobbies , terrace,  entrances and exits of the property in use i.e. that area which are free to use by all the owners of the property.

- In your case , the inter connected passage between the houses ,open  car parking area and the area which you all all using mutually & jointly come under the common area. 

De ar client, 

As there is no land demarkation done with respect to the interests, there can not usually be any breach of rights. But if you have stayed there for a considerably long amount of time, say 20 years then you can claim it is your interest of the land and it will account to breach if they enter without consent.

Thank you.

None of co owners can barge into your house without your consent 

Install CCTV cameras in front of your house and in living room 

- A house is the internal occupied area by the owner with the personal liberty , and  this portion not come under the definition of common area , and hence none having right to enter and use the same without getting the consent of the owner of the house legally. 

-  Further, if any trying to enter or use without getting the consent then a compliant can be filed . 

You are entitled to privacy and peace inside your own house. If anyone enters it without your permission, it amounts to criminal trespass, and you are entitled to lodge a criminal complaint against that person.

The parking space, common passage, staircase and the open terrace (if any) shall constitute  as common areas, including the lifts if any and other open spaces.  

Nobody can barge into your dwelling house for any reason, if at all he expresses his rights over your proeprty, he has to approach court seeking an order to dispossess you and take possession of the house property for the reasons he relies upon. 

If anyone indulges in such activities, he may be termed as an illegal trespasser and you can take criminal action agaisnt him for trespassing offences including theft and dacoity

No they can't they need to give you advance notice and idea. They can only come in their share as matter of right not in your share