For Wang Qiang, as long as he had the support of Wang Sheng, the diamond-tier expert, he didn't need any other helpers. Moreover... with their current identities and status, finding subordinates of the purple crystal tier was incredibly easy.
This time, the plan was to eliminate Xin Yun and the others first, and then have Wang Sheng take action to kill the duo, framing Xin Yun and his group by claiming they died at the hands of an enemy. That way, there would be little resistance within the gang. Even if there was hatred, it would be directed at Xin Yun, who had already died.
It's worth noting that when the Two Great Protectors, Qing and Hei, were defending two small cities, they each had their own followers. The current Dragon Head Gang is a merger of three smaller city forces. If the Two Great Protectors were to be eliminated, the whole Dragon Head Gang would fall completely into Wang Qiang's hands.