Fellow experienced rescuers, I have a dilemma. What do I do with these kittens?

One of my workers just found 3 kittens, approximately 4 weeks old. I currently have 6 indoor cats of my own and am fostering one that is to go to his new home in about a week. If I take these 3 cats in, it means round the clock bottle feeding, etc. We are almost maxed out time-wise as it is. There are no rescues in my area that will take them this young. If I don't take them in and leave them to fend for themselves, if they survive, they will turn wild and add to the problem. I have managed to trap/spay/neuter most of the cats that people have dumped at our place of business. There are so many out in the fields that there is no way to get them all and sometimes kittens pop up. Timing is bad. So, do I suck it up and take them home until they are weaned and healthy and then take them to the shelter or do I see what nature does? I'm so frustrated. This year we've seen so many dumped here it's unbelieveable. Please give me your kind opinions on what you would do.