If I am correct it is male Newton - originally from Fossil Rim - and females Mashile and Martina. Incidentally, Martina is Mashile's calf.
Given the close family ties both females will never breed if the current set up is maintained. Does not occur that way in the wild; when a new calf is born the sub-adult female older calf is chased off by the mother and will settle with an unrelated female.