Blackbird chick/fledgeling advice?

I had a little blackbird once and made the mistake of making it too tame and it followed me around and I had to take it to a wildlife rehab station. Trauma for both of us. So I would suggest just leaving them alone as much as possible. Their instinct will take over and they'll learn to fly in no time. They should be fine. Just try and make sure they're safe from dogs and cats and that they're close to the ground and if possible there's good ground cover - the parents should still be around to look after them. Good of you to care for them and respect that they are wild creatures.