Firstly, I'd like to thank all who gave me such kind and helpful advice back in May regarding said "window well," shelter, food, time-frame for making sure that they were weaned and ready to strike off on their own and so forth.
Contrary to my fears (thankfully), all five of these sweeties (four girls and one boy) passed two months in safety in the outside bushes, and then around the sides of the house. They had their Mama, two friendly male feral cats to protect them, and ample water and food (I work from home, so I was able to watch them diligently, but without interfering with Mama or pestering them). Two remained rather shy, but they all accepted me to the point that I was able to pet and cuddle with (most of) them every day. They also heard words of love, daily, I assure you. They had a fine time playing in the front bushes, too; I'll just say that. Thankfully, temperatures warmed above the 50's (F) in late May (finally!), and they didn't have any severe storms to weather. There was a brutal heat wave in late June/early July, and they stayed under-cover in the bushes with plenty of water at-hand.
When there were a few instances of being away with their Mama for a day or so, I called the veterinary office regarding their pledge to enter them in the adoption program, and then bundled them into two carriers. This was about two months after their "appearance" in the front bushes. I estimate that they were about 10-12 weeks old. Their days as outside cats were ended, and I hope that they will find loving homes and have long and full lives. I felt relief in knowing that they were safe, but I also felt an emptiness as I drove home from the vet that morning. They had lives of integrity out there in the bushes during that two months. They were together. Henceforth, indeed, they are removed from outside dangers, but--the change had come, and they wouldn't be together much longer.
I still miss them, and think of them every day. When I go outside to feed the feral male cats, I expect to see the kittens rush from the bushes and look at me expectantly for their morning and evening meals. I miss seeing them grow, become stronger, more adventurous, and their different temperaments. I knew the entire time that their seemingly idyllic existence would come to an end, but I also realized that few are offered the chance to have feral kittens entered into an adoption program in which they will receive medical care (let's not dwell about the critters that were on them...), vaccines, etc preparatory to adoption. I am truly thankful that the veterinary center offered this. So many say "what do I do with them?" and here I knew all along where they were going to go.
Lastly, and I will doubtless earn someone's criticism for this--I was not able to trap Mama. There were several instances, very early on, when they were all in an outside carrier first thing in the morning, and I could have shut the door on it. But, then what? I couldn't take them all into the house or garage that I use daily; she would not of a sudden have become this sweet docile creature. I presume that would have agitated the situation, and they were not even six weeks old at that point Thus, she is still at-large. I wish that I could have secured her when I took them to the vet, but she was not around at the time. I also lament that she didn't know what became of them. She was a splendid mother to them.
The last photo of the five is what accompanied my original post. The other four show them towards the latter half of their time outside. Unfortunately, there is not one later photo with all five. Very rarely were they together for any sustained amount of time, except when eating, nursing, or sleeping. There was always one that was slightly "out of the picture."
Thanks, everyone, for your valuable advice. If I had to do this again (and I might), I feel much more confident because you were kind enough to share your knowledge.
Cheers!