Could we delegate a worker only to a manager or also to a simple employee in workforce compensation?

Summary:

Case : one line manager would like to delegate a worker in his worksheet to another person for the review of Salary increase during the compensation campaign. Unfortunalty, when he tries to search the name of the futur reviewer, he can't find him in the result.

Do you know why ?

The futur reviewer isn't line manager in Core HR, is it linked ?

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