My feline problem

This sweet pie is not so sweet when the stench of pee and poo accumulates in my previously clean void deck. Sorry if this sound elitist but the area usually smells clean and fresh. This is due to the design of my flat, the void deck, being not void but like a condominium that has units on the ground floor, and thus individual home owners keep the area very nice and clean. But because of the 8 cats running around outside this one flat on the ground floor, the place is exceedingly smelly.

Let me explain.



There used to be 3 grown cats and they were adorable. Then they had a litter of kitten with 4-5 new kitties. These babies are cute but the increased in population has led to the floor being dirty, stained and reeks of an overwhelming stench of amonia. What is worse is recently I heard the calls of a kittie in heat and I can almost expect another litter to appear around my flat. I do not understand why the kitties do not poop in the grass right in front of their unit but they don't. The increase in population has overtaken the environment's natural ability to neutralize the wastes. The family also does nothing to create toilet facilities for the felines. There are no litter boxes. Food is served on plates but at the same place where the cats pee and poop. I know they try to clean up at night as I see them mopping the floor outside their homes sometimes but I still smell the stench increasing everyday. Technically that area is public corridor and it's right beside our letter box.



I really love these kitties but the neighborliness-irresponsibility is overwhelming. Unfortunately due to certain religious or ethnic sensitivity, I am afriad to approach the family and suggest neutering the cats. I thought of writing a note and slipping it into their letter box but that would be quite irresponsible. I honestly have never spoken to this family and it kind of intimidates me. How do I make sure they know I really do love cats and have all our interests at heart? How do I get the guts to do something about this? Or maybe there is nothing I can do because it's none of my business? Should I respect their choices? It is worth respecting? Do I have a right to do say something? What happens when there are MORE cats?! These cats are not feral but they get to run about the neighborhood and do not ever enter the house it seems. I cannot suggest adopting them and I do not want to disrespect the owners by sneaking them off to neuter, god forbids! Besides what if the owners do not want to give them up and enjoy the multitudes of cats?

What should I do?