Excuse my ignorance (I'm originally from England), but what is "Chofetz Chaim"? A kehilla? Yeshiva? Is it affiliated with Rabbi Zaks in Monsey?
Chofetz chaim is both a sefer, and a person. The person wrote the sefer. He lived in Radin, and had a yeshiva, and wrote the sefer. He is Rabbi Zaks' grandfather or greatgrandfather or something. Why is Rabbi Zaks' name not Kagan? I dunno, why is your name not Avinu if you're descended from avraham.
There's also some orgs that incorporate his name. Like the chofetz chaim heritage foundation, as if the chofetz chaim's heritage is everyone watching a movie on tisha b'av afternoon, with a frum version and a frei version.
Obviously, the chofetz chaim's real heritage is the yeshiva named after him, that was opened by his nephew, whose name is also not Kagan (I ASK YOU AGAIN, IS YOUR NAME AVINU? NO? SO I DON'T WANT TO HEAR ABOUT IT).