Sharing expenditures on a public yard

There are two entrances to our building, one in the front and one in the back. How should we divide the expenses of caring for the yards? (Officially, both yards belong to the owners of all the apartments in the building.) Those who own apartments in the back entrance will pay for the care of the back lawn, and those who own apartments in the front entrance will pay for the care of the front lawn. Owners of all apartments will share the expenses of caring for both lawns equally. Owners of the back entrance apartments will pay 75% of the expenses. They will have to fully cover the expenses of caring for the back lawn, and also half the expenses associated with the front lawn, since they have to pass through the front yard when they leave the building, so they too have a share in enjoying the front lawn. The owners of the front entrance apartments will have to pay just 25% of the expenses, or half of the expenses of caring for the front lawn. Thank you  

Everything depends on how the expenses a normally divided. If all the expenses for the upkeep of the building are divided equally between all the residents, irrespective of the entrance wherein they live, then the expenditures for caring for both yards should be divided equally as well. If, on the other hand, each entrance maintains a separate account, then each entrance should pay for the upkeep of its own yard.  

Shulchan Oruch, section Choshen Mishpat, ch. 161