I wouldn't say 2 is a cockerel yet. 1 looks to be one. The others are pullets. Post updated pics showing whole bird for ID, in 2 weeks.
Please take a look at my sticky in this section for tips on taking pics for ID.
People on FB chicken groups don't have the brains God gave an animal cracker. I've seen them identify a black game hen as a vulture.
I agree that she's likely some sort of egger mix.
I remember when mom would send me into the corner store to buy her cigarettes at 5 years old.
Dang near 30 years (Yes I'm a young one :plbb) and 2 kids later, I get carded every time I walk into an ABC.
What color is their skin? Look at the soles of the feet. Yellow = bantam Rock. White = OEGB.
That being said, it's not uncommon to see hatchery OEGBs with yellow skin. Watch their body shape as they mature. Rocks will be more robust, OEGB will be gamey.