So, yesterday we found two kittens, probably around a week old (their eyes are starting to open, but they both still have umbilical cords, most likely because the female we think is mommy to them is a new mom and hasn't helped them with it). We named the two of them Leo (orange tabby) and Panthro (black head, grey body) and gave them formula and left them in a box in the yard, hoping that mommy had just been scared when we found them and that she would take them out of the box. Every couple of hours we came out to check on them (our cats are mostly feral, although some are better around people than others, but some of the females will not come into the yard with people around) and the kittens would feel warmer at some times than other, and several of the times they were warm they also felt like they had full bellies, so someone was coming in and checking on them. We left them in the middle of the yard during the night, and brought the box onto the shade on the porch during the day, making sure they didn't get too hot or too cold, and fed them every hour if they didn't feel full.
Tonight, while we were moving the box out into the yard again, two small kittens came into the yard by themselves, too small and young to be in the yard (we've gotten really good at telling the age of a kitten just from the size of it from across the yard) and since no adult came into the yard with them, I went over to grab them. They seem to be closer to three weeks, they had the start of teeth and eyes were fully open. They were able to walk with their bellies off the ground, but they didn't see me until I was within a couple of feet and when they "ran" I just had to take one more step to grab them both. Both are male (I think every single one of our kittens currently is male, if not the vast majority of them are) and we named them Ash (bigger and solid grey) and Soot (black and grey, more black than Panthro). They were really hungry, so we fed them from the bottle, and put them in the box with Panthro and Leo, thinking that if they belonged to one of the two females we thought, they were cousins and could keep warm together.
Once all were full and comfy, we went inside, planning another night of checking every couple of ours. Within half an hour, Cross, one of the two females we thought could be mommy, came into the yard and grabbed Ash (I think, was dark out and I didn't want to scare her) and carried him out of the yard. I watched for a bit longer, but she decided to nurse him by himself before coming back for Soot. Another half hour went by, and I had heard the kittens cry for a little bit again, so I was sure she had come and left again, but when I looked out there, she was laying by the box again. I went in and waited a bit more, and the next time I looked she was gone, not in the yard at all. I went to check who was in the box, it was back to being just Leo and Panthro again. As I turned away from the box, I saw Fox in the darkest corner of the yard, Fox being Cross's sister that we thought might be the other mother. She didn't run when I went to the box, so I am hoping that she takes her kittens, but if not, we will continue to move the box into the shade during the day and into the yard at night. If she doesn't take them by the time they are closer to three weeks old, we will make it so they can follow her out of the box so they can start eating solid food. I will post updates and more pics as I have them.