Your chicks do not seem to have the darker marking on the back and so-called brown markings as shown on ItsAZOO32 pic of one her chicks, which is definitely a dark brahma chick
Could you tell me about your Dark Bantams. What line are they out of? Do you show them? How long have you been breeding them? Are you an ABC member?
I breed/exhibit bantams in Buff and Light. My son has a few large darks. Might be interested in a start in the Bantam Darks...depending on the line.