You should have the genetics calculator for chickens.
I just ran the Lavender roo over Buff Columbian hens (which yours *mostly* are, though they don't have black at the hackles) and it was as I thought...black chicks, both sexes.
Here the calculator.
http://kippenjungle.nl/Overzicht.htm#kipcalculator
I just ran the Lavender roo over Buff Columbian hens (which yours *mostly* are, though they don't have black at the hackles) and it was as I thought...black chicks, both sexes.
Here the calculator.
http://kippenjungle.nl/Overzicht.htm#kipcalculator