@Frank *********
other than they couldn't get the ED visa before they come here no. you'd need to get them here, get them enrolled in a school, get the documentation THEN apply for the in country Non-ED visa
Where as IF you got them a 90 day Non-O visa based on being the child of a foreigner holding an OA visa when YOU get your visa, they'll come in, get 90 days, and then you go to the immigration office and get them a year extension that matches your year entry stamp