I am going to open up a can of worms here. Certainly TNR is a great solution when you are dealing with feral cats and certainly can often the most viable option. However, bear in mind it is a long term commitment. You are going to be making the commitment to be the guardian for these kitties and provide them with the necessities of life. Under the right conditions, with proper care and food and shelter, cats can have the potential to live for many years outdoors.
I noticed that you are renting an apartment. One of my concerns would be, how long do you expect to live where you are now and what will happen to these kitties if you should move? Would there be someone else willing to take over the responsibility for their care after you leave?
The other option would be if someone were willing to socialize them so they would be adoptable. You say these kitties are likely no more than 4 months old. Kittens can be socialized most effortlessly when they are under 8 weeks old. However older kittens can also be socialized if someone is willing and able to put in the effort. If you feel that you will not be able to make a long term commitment to these kittens, you might still want to contact some rescues and tell them the situation and see what options they can suggest or even whether or not they may be able to take them on.
"The animals share with us the privilege of having a soul." -Pythagoras
"The soul is the same in all living creatures, although the body of each is different." -Hippocrates
"Let us be loving, hopeful and optimistic. And we’ll change the world." -Jack Layton
"Be the change you want to see in the world" -Gandhi
Kitties: Punky (17), and Sassy (13), Twinky (10),
1991 to May 24, 2009