On behalf of is a phrase that is commonly used in formal writing or speech to convey the idea of representing someone or something. However, there are several other synonyms that can be used in place of this phrase such as "in the name of," "representing," "as a representative of," "on the part of," "substituting for," or "in lieu of." Each of these phrases conveys a similar meaning and can be used interchangeably depending on the context. They are all useful in conveying a message of standing-in or acting on someone else's behalf and are essential in professional communication and diplomacy.