What lovely mares :)
Misty looks like a beautiful example of a smokey brown to me. This is similar to a buckskin, but instead of cream acting on a bay coat, it is acting on a brown coat.
Fiona is a bay based dun if you ask me. If she does indeed have a dorsal stripe, she has the face darkening, the stripes on her legs and the barring on her shoulders/withers. Classic example :)