You will most likely have to do some test breedings with her. She appears to be a true Mottled, her feather pattern looks like it has the V or diamond shape tips that it should have. It would help to show pics of her from above, straight down to see her shape. From this picture, it looks like she has some stiff feathers in her cushion, so you would look for a bird with a very soft, full cushion, and a shorter, deeper head. Right off the top of my head, I would suggest a Mottled rooster to start with, see what you get, then take one of those cockerels back to this hen. Look for one of the genetics threads and see if you can get some serious help with this.