This is a very tough situation for your assistant manager. Going from peer to boss is a transition which requires a lot of tact. I suspect that she is not yet confident in her new position. This may be one reason why she is doing the work for her team. She still feels comfortable in that role.
I have a few recommendations for you as her boss and for her as the new manager.
First my recommendations for you: Have a candid discussion with her. Let her know that you are aware of her doing the work for her team. Tell her clearly that in order to succeed she must establish boundaries with her friends.Assuming that they are doing good work, firing them is not the answer. Your assistant manager must make a decision on how important this opportunity is for her and what she is willing to do to be successful. This is just the first challenge that she will encounter as a manager and she needs to learn how to deal with difficult situations.
My recommendations for her: Meet with her team, together or individually and have a similar candid conversation with them. She should take ownership of the problem. Let them know that she has been having a hard time separating their friendship from the job requirements, but in order to be successful, she has to learn how to give out assignments. She wants to be confident that they will carry them out. Let them know that by doing their work, she hasn’t been performing her new duties as manager. Ask for their help and suggestions on how to keep work separate from their friendship.
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