Do you know how many eggs of what colors hatched? That can sometimes help with sorting the chicks.Just for curiosity, but I think the mom of this chick was a WJG. Which got me thinking, how come it's the only one that looks like this? I know it's genetics, but thought I'd as anyways . I have another chick with some of the same coloring, but again, only one that looks like this:
P.S.: This pic is about 2-3 weeks old; the chick is bigger now, with a much bigger crest. She/He has the biggest crest out of all
(You can see the white chick with black "sploshes" as well )
Any pairing of not-barred rooster (Spitzhauben) with barred hen will produce sexlink chicks (barred sons, not-barred daughters.) So if the Spitzhauben is the only rooster, then ALL barred chicks are males. There are probably an equal number of not-barred chicks that are female.
White Jersey Giants are "supposed" to be genetically black, then turned white by the recessive white gene. That would produce only black chicks when crossed with a Spitzhauben. They should not be able to produce a patterned chick like the one in your photo.
Do you have pictures of your Olive Eggers/ Easter Eggers? That may help sort some of this out. I can make a reasonable guess about the genes of the Silver Spangled Spitzhauben, and Silver Laced Cochin (black lacing on white), and White Jersey Giants (unless they are some other white chicken pretending ot be WJG), but "Eggers" can have a wide variety of colors and genes.
The white chick with black blotches is probably a genetically black chicken with one copy of the Dominant White gene (turns black into white, but can miss bits.) So the mother may be one of your "White Jersey Giants," except they may actually be another breed or else have genes their breed is not "supposed" to have.