Situ Xin had reasons for her actions; both the Situ Family and the Loo Family, not just Situ Che and Loo Jie, who would stay in the special forces, Situ Jin and Loo Bun would also need to pass this test in the future. And she did not want the same incidents to happen again.
Situ Xin hadn't informed these old masters about the situation with Jiang Anbang, instead, she asked The Dark Division and Dragon Society to handle it for her. She felt that it was inconvenient for these elders to take action, and besides, if the family elders did take action, it might not have resulted in what Situ Xin had desired.
After all, they were still controlled by someone higher up. That someone would be pleased to see the people on both sides fighting each other to death and would step in to mediate when they had almost exhausted themselves to reap the benefits. This was not what Situ Xin wished to see.