Some Issues on the Usage of "behalf" in English Everyday life and customs

So what's the difference between "in behalf of "and "on behalf of"?
I am trying to find answers from English dictionaries.
But I found that they seem to have many similar uses.
Are there native English speakers willing to answer this question? Thank you!

Honestly never heard "in behalf of", only heard "on behalf of"

"In behalf" of means “for the benefit, advantage, or interest of” in acting as an agent, friend, or benefactor. Another way to think of it is “as helping” someone or something. "On behalf of" means “as the agent of,” “in place of,” or “on the part of.” Another way to think of it is “as representing” someone or something.

"In behalf" of means “for the benefit, advantage, or interest of” in acting as an agent, friend, or benefactor. Another way to think of it is “as helping” someone or something. "On behalf of" means “as the agent of,” “in place of,” or “on the part of.” Another way to think of it is “as representing” someone or something.