Parking rights in a building - Builder floor vs Ground Floor

Few years ago, I purchased the first floor of a 4 floor 100 sq yard building (Ground, 1st, 2nd and 3rd) which was originally the builder floor. All floors except mine are owned by the original owner - a senior citizen couple who live on the ground floor. Their son and his family live on the third, while they have rented out their second floor. The only parking space is on the society road, beside the building. It's a very small space where one can very tightly fit a car and a 2 wheeler. Now there are 3 vehicles in the entire building. My 2 wheeler, and their son's 2 wheeler and a car. Now, I'm aware that legally the ground floor gets the first preference in parking and I respect that. What I want to know is if I am allowed just a two wheeler space. Also, in case I decide to rent out my floor, can my tenants park a 2 wheeler in my place? The second floor tenants don't have any vehicle and even if they did, they don't intervene out of fear of being evicted. The senior couple and their son own 3/4th of the building since a long time. Also, few months ago, when they had sold their car, I talked to the couple and they allowed me a 2 wheeler space. But now that their son bought a new car, they allow me to park only when the car is gone. I have asked them to adjust a bit but they don't listen.