Merit and karmic debts exist in a state of mutual offset. The Heavenly Dao is impartial; it can't be that, for doing good deeds all your life, just because you committed a wrongdoing or were implicated by others, all your previous good deeds turn to zero. That clearly wouldn't be fair.
So, as for what the Li Family did, even if the consequences echoed onto Li Changxi, it actually wouldn't be too much, at least her own merit could definitely cover for it. Like the killings caused by Ji Changsheng, his merit could definitely cover for it as well- however, even though it could cover, no one would wish to have karma clinging to them.
Li Changxi wishes to transform the Li Family and with Ji Changsheng's logic it could be completely understood. As for whether the Li family understood, Ji Changsheng did not care.
"Where is the Third Prince?" Ji Changsheng continued to ask, "was he also knocked out by elder sister?"