Hiya, Welcome to the forum
I have been working with Tammy, and also am working currently with another breeder to establish white lines. I had a white robo myself from which I bred five whites. I am now breeding one of those whites and have from his first litter a white girl here at the moment, there was another white in that litter but sadly it didn't make it.
I have just had a litter born today from my white boy and Wessex hams husky girl which hopefully will produce more whites.
Markisia is lovely, do I see a small brown spot on her head? If so she isn't actually a white, she falls in to the category of Pied robos, just being a very diluted version.
Hamtastic has two lovely diluted Pied girls Leela and Dora, if you have a look through for her pics you'll see they are very similar.
The whites don't have any brown marks at all, they do have a little grey stripe on the ears though remaining from the mutation from husky which created whites.
Here's a good shot of the front and the back of whites, two of my boys from my first lot of breeding.
Here you can see four of the five white boys. The second from the left as you view it looks like he might have a brown dot, it's actually a scab where he got bitten on the bum ouch!