Plucking photos from the facebook group for Olandsk Dwarf for this, none are mine. Lucky find lol. It's just got good examples. Only place I've personally seen Olandsk Dwarf chickens before this was greenfire, which show an e+ hen with mottling, then a few millie fleurs in their photos for the breed, so I was guessing that both genes are present within the breed. The group seems to line up with this, there is a lot of variation in the birds present on that group.
I wasn't expecting solid white chicks, haha, but that's because of the mottling, and I'd presume those chicks to be the more excessively mottled specimens as adults, like your hens.
View attachment 3709390
The two dark brown chicks in this photo, i think, are eb based. That's the color millie fleur d'uccles come in, also eb based birds. I can't tell on the white chicks, too much of their pattern is camouflaged. eb can also present with broken head stripes and a whole lot of extra eye stripes, it's got a lot of variation.
https://www.facebook.com/photo?fbid=7070814342982154&set=g.178654882329474
View attachment 3709392
These chicks are e+. Strong head stripe, clear eye stripe.
https://www.facebook.com/photo/?fbid=2747671675372623&set=g.178654882329474