Yang Fan didn't take action against Tan Mingde for his own deep considerations. After Tang Yao left, he left a mess. Although there were many debts, it was also a valuable property. If managed well, money could definitely generate more money.
As Tang Yao's sister, if Tang Ziqing could be lured onto Yang Fan's side and absorb Tang Yao's industries during the opportunity, Tang Yao's old subordinates would definitely support Tang Ziqing. Feng Zhiming is a businessman; everything is based on benefit. He could cooperate with Tang Yao in the past, and now that Yang Fan has replaced Tang Yao, of course, he could continue the cooperation—who would go against money?
Only a brainless brute like Chu the Tyrant would end up failing, and only a clever rascal like Liu Bang could conquer the world.