Hmm, they could be some british alpine in Savannah as she has turned blue roan in the winter. She doesn't look like it's Anglo-nubian at all, although it could be something more unusual like an old English. My neices milker changes colour too, although not to such an extend as Savannah! She is british saanen x british toggenburg, and she goes ever so slightly roan, and more so in winter. She gets dark patches underneath her eyes.
Beth