Oh how sweet they are. The broody will take good care of them. Two things I see which may be a problem. First, the water in the bird bath might be a danger the first two weeks. Chicks are drawn to water in the first week or two, and they will jump in a deep pan and drown. So I would cover it with a screen for 2 weeks, then it will be safe later. The second thing is that they shouldn’t be eating scratch grains. They need a balanced chick starter or flock raiser, which your older chickens can eat as well, as long as you put out some crushed oyster shell for the hens to take as they need for egg shells. Once the chicks are about 20 weeks old, you can change back to layer feed. Scratch should only be used as a treat, and chick grit is needed to digest any foods other than chick starter.