The green blood with being split BS will end up like this, some high percentage spaldings with split black shoulder will look almost like a BS peacock with just a few bars on the back.
BS has always thrown me for a loop as well especially when you throw some green blood in there. I have mixed feelings over the split to BS dark spots on the shoulders. I had a 15+ yr old rooster start to change his colors late in his life and that pattern showed up but he had never produced a BS chick with our free range BS hens. He is long since dead as my neighbor down the road shot him for tearing his sliding glass door apart. I am still confused about the BS split pattern and cannot be of solid help.
I believe in fact that there are many split BS because ordinary breeders believe they will create a NEW color with a crossing of IB and IBBS.We need IBBS .... don't need IB split BS!... they still rare !
I think it's more the fact that you never know with hens whether or not they are split and as this thread has shown it's still unclear whether or not you can with males either. I've sold any and all of my IB BS birds just because I have midnight bs and if the hens ever got mixed I couldn't tell them apart. I could see the color thing coming into play but not as much as when it comes to white and pied.