page not found url based on different channels

Hi Kentico team,I have three different channels(sub directory/content tree) under one root(master page) having sub master page each. Whenever user in channel 1 types wrong url it should take them to 404 custom error page of channel 1 content tree. And for user tying wrong url in Channel 2, it should take them to 404 custom error page of channel 2 content tree and so on. How do we achieve this? I set up 404 error page in setting-@content(Page not found URL) but it is only for global. I am looking for channel (or) Sub Content tree specific, so that site header of individual channel remains the same.Thanks in advance.