As you know, the last birth did not have a happy end - the baby birds finally took flight and flew right into the pool.
i had a similar experience. A nest was built in my chimney and the babies fell into the grate. I dumped them into a wicker basket, carried it back to the roof and wedged it into the chimney top. I wired an umbrella to a metal pole that used to hold the TV antenna to protect them from the elements. So they were back in as much as the same situation as I could manage,
The wildlife center said I needed to feed them them in case their mother didn't come back, so for several weeks I dug up worms and mixed them in the blender with raw egg yolk. (This is what the nature center recommended.) They let me feed them, so 5 or 6 times a day I climbed the ladder and fed them, until one day I saw the mother bird and some droppings and knew they were probably fine.
I never saw them fledge, but one day they were just gone. The following summer, I found that some of them had landed on the part of the roof I had recently tarred. I hope one or two of them made it, especially after all that work!
I never used the blender pitcher again, BTW.