in one's behalf
in one's behalf or on one's behalf {adv. phr.}, {informal}
1. For someone else; in your place.
My husband could not be here tonight, but I want to thank you on his behalf.
2. For the good of another person or group; as a help to someone.
My teacher went to the factory and spoke in my behalf when I was looking for a job.
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Source: A Dictionary of American Idioms