Is retaliation obligatory if a woman kills her husband's brother, and the resulting right to Qisas transfers to her son?

Primary text

If a woman kills her husband's brother, and the right to Qisas (or a portion of it) devolves upon her son, the Qisas is invalidated. This holds true whether the right transfers directly to the son or transfers to him via inheritance from his father or another intermediary. The ruling against Qisas is applied due to established legal impediment.