Happy to help! You're getting good at it! About six months ago when my second batch was getting their feathers, I noticed the color thing and asked about it on here. Another person confirmed that they had known about it and wondered why most don't mention it. She said it works with all "lace" ducks. I assume that means ones with pencilling.
Thanks! I love learning things like that. I spend so much time observing them and trying to find differences.