The official Scapegoat has resigned from his position and refused to play the part any longer. So the family is desperately (though unconsciously) seeking someone else to fill the position. It seems to be moving toward the younger sister. This family values intellect and the younger sister is rather emotional. She has been labeled a "drama queen" by the family (notice the negative labeling which precedes the scapegoating).
There's just one problem. Though she may be a drama queen (and she can be a bit), she actually has a very serious and very real situation going on right now. A situation which would typically require the family to band together to support her. But it appears that the family is using the "drama queen" designation to deny the validity of her problem and, in doing so, eliminate their responsibility to support her. This tactic also denounces her emotional reaction to the problem as merely being "drama". By defining painful emotions as "drama" other family members can avoid feeling them. They avoid having to listen to her experiences and her pain. And they put her down for experiencing them.
Though I detest the American culture's tendency toward anti-intellectualism, using intellect as a way to avoid feeling your emotions or to "one up" someone who has painful emotions you want to avoid is not the ideal either.