TIFU by trying to save a baby sparrow

While doing yard work I found a blind, baby sparrow that had fallen out of its nest under the eaves. I had just cleared out two empty nests but was leaving this one since it had two chicks in it. Anyhow, I found a sturdy stick and got it to climb up on it and moved it to some shade until I was done with the work I was doing.

Later, my wife came out with our dog (korso-lab mix) and I warned her about the chick (so that the dog would not get it) and she suggested we put it back in the nest since I hadn't actually touched it. I couldn't quite reach the nest so I asked my wife to get me a step-stool. Worried that the chick would jump from the stick we quickly got the stool in place and as I reached up the other chick panicked and jump on the ledge of the nest.

I knew what was about to happen but it happened so quick I couldn't verbalize; as I lifted the chick on the stick into the nest the other chick fluttered down into a garden box and our dog immediately dove in. My wife shooed her away but in doing so scared the bird further and it jump from the garden box down to the ground right where the dog was waiting.

The tragedy of the whole thing is devastating because the other bird seemed much more healthy and more ready to leave the nest than the blind sibling that fell out of the nest. Because of my intervention to save a bird that will probably not thrive another bird that would have got eaten alive by my dog.

TL;DR: My attempt to save a sickly bird that fell from its nest resulted in its healthier sibling jumping out of the nest to be eaten by my dog.