If you choose to hire the Business Manager based on clear business benefit, then the next task to is mitigate the risk of the other employees acting out due to the change.
1.Salary
a. Is it possible to keep the compensation and contract details private?
b. If other employees will be aware of compensation due to the company size or you choosing to tell them, then you may want to take steps to address the issue by first differentiating the role. (e.g. How different is this role from other current roles at the company? What is this person responsible for compared to others? What are the Key Performance Indicators for this role and what is the penalty for not meeting them?)

2. Change Management
a. Change in general can cause people stress. If bringing someone new in will cause issues with current employees, it is important to both try to understand what those challenges may be as well as know what you find as an acceptable loss if people choose to leave.
b. There are many Change Management techniques that can be implemented to help with smooth transitions.

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