Determining gender of Breda fowl, any suggestions?

[gritsar]

I know how to sex most breeds, based on the secondary sex characteristics that show up at 4 to 6 weeks old, but without a comb on the Breda I imagine the task will be a bit more difficult.
Any suggestions?

I have nine from a top breeder - six blue, one black and two splashes, all 3 weeks old.

Any help woutd be greatly appreciated.

 

[Jennet]

I have 4 Breda chicks at 3 weeks old. Tried vent Sexting them but still can't tell? Any help would be great!