URGENT - Help and advice on chick protection!!!

Hi All

I'm new here and don't know much so any advice welcomed.

There is a lovely pair of what I think are blackbirds living in and around the garden. They have been getting harrased by two magpies. Earlier today there were feathers flying. I went out and a magpie flew off chased by the two blackbirds. Left behind in the garden were two very scared chicks (fully feathered but not able to fly). Mum and Dad are still around and trying to feed the one chick I can still see hidden by the fence. I am worried about when the local cats are on the prowl plus magpies foxes etc. What can i do to help?? should I put the chick in a padded box in one of the trees in the garden Ive seen the blackbirds in? I dont know where the nest is.

Any advice greatly appriciated.