Alloting parking area for tenats in individual bungalow/property.

We ve rented one individual premises for preschool & daycare.while registering agreement,landlord did not mentioned about the covered parking slots,whether they are giving it or not,though we have rented all 4 units of the building.we were in the impression that its compulsory to have covered parking if all units r rented by us.its our mistake.it was clearly mentioned to them that we r going to use it for a school.they insisted to keep their car in parking area .we agreed for the humanity purpose as they are going to Bangkok.Now ,They are asking us to use only uncovered parking area as play area for preschool children.& kept their car in the middle of covered parking area which is causing obstacle to use that premises as a school. we agreed to give some extra rent for covered parking area also. but they demanded 35000/- for it which is very unreasonable. bcz whole property's rent is 75000/- is there any law about compulsory parking space to individual property tenants? what to do in my case to get the parking area ,because its our prime necessity to have play area for school children?