Thanks...hoping you don't take that as inappropriate. That wasn't a for sale post. I haven't sold any hatching eggs or birds. Just an offer to you to help get you some BCMs.
They all look very similar as chicks. But your saying she has leg feathers, but yellow feet.
May have Marans in her, but not pure. As @JedJackson stated... barnyard mix.
She's still young, just lightly feathered legs, she should have slate legs/pink feet, copper in her hackles should start appearing any time, but don't freak out if it don't. I've got 2 all black BCM's with no copper.
The white in feathers is normal and she should molt them out. Any white after...
She looks like she has Marans in her. She have pink feet?
How old? And where did you aquire her?
If I was guessing, I'd say Black Copper Marans or a hybrid like Midnight Majesty Marans is one name Hatcheries use.
Why don't you think she's not a BCM?