Pets

Hi everyone,

my next door neighbour has a cat and just a few weeks ago they informed us that she was pregnant and was due to have the kittens any day.
We never saw these kittens and then found out via somebody else that the poor cat had given birth to two kittens but they had both died.
Now I see that there are two little kittens out with the mother and all they do day and night is sit on our outhouse roof and cry... non stop.
We asked if the kittens were hers but were told that they weren't and, because hers had died, they got two new ones out of our local paper.
The mother is SO skinny and you can clearly see her spine and her ribs when she walks. The kittens are absolutely beautiful but, again, they seem very skinny.
I just don't think they are being well taken care of... or fed as much as they should be.
We have also found out recently that another cat they had got really badly injured by a dog a few doors up and, instead of rushing it to the vets (as I would have), they didn't bother to do anything and the poor little might died in the garden.
Instead of burying the dog like most people would they put it in a black bag and left it out for the binmen!
I can assure you that if I had know this BEFORE then I would have done something about it. However, this happend about a month ago and I have just found out.
What I would like some advice on really is what I should do. I really don't think they are looking after these cats properly and I'm just not sure if I should get involved.
We live in a house but they live in a flat next to us and every morning I see them open there upstairs window to let the cats out and then close it again until late in the afternoon.
The cats spend pretty much all day up on our roof and I have now started feeding them and leaving water out for them.
What should I do? Something or nothing?