代理 (主管, 首席執行官) Acting (Chief, Superintendent,CEO)
Example; Before we hire a new CEO, John Smith will be the acting CEO for Genetic Biotech.
Designee: a person designated to carry out a duty or role.
Example: In my absence, Jane Moon will be my designee and will sign any paper on my behalf.
Designate: a person appointed but not yet taken the office
Example: She is the Mayor Designate.