Premise: Father Xmas is a 2001 short film from director Marie Rose and the American Film Institute's Directing Workshop for Women starring Dakota Fanning as six-year-old Clairee who learns from her older brother (Stephen Fanning) that Santa Claus is not real and that their father is fighting in the Vietnam War.
Hypothesis: Father Xmas featured a young Dakota Fanning who was not subject to the screen actor's guild pay guidelines because of her young age.