I don't really understand the laws of shlichut, designating a proxy to perform a mitzvah so I hope the question makes sense.
Does someone have to assign me the role of shaliach on his behalf, or can I (knowing he will not be mekayem the mitzvah otherwise) take on the role of shaliach and perform the mitzvah "for him" as it would be to his advantage?
The text of kaparot in my machzor includes "zeh chalifatchem" which is, according to the notes, said by one man on behalf of other men. Must they have said that they want to be exempted through someone else?
Can I give matanot l'evyonim on behalf of my family or friends who aren't going to do it, even though none of them (family or friends) has asked me to give on their behalf?