I was under the impression that multisite_icons_and_actions is deprecated and we should write a subclass of Icon instead (like those in lib/python/cmk/gui/plugins/views/icons/builtin.py). For multiple icons probably multiple such classes are required. I wrote such a subclass and placed it in ~/local/share/check_mk/web/plugins/icons/foo.py. It’s just one icon, though. But when I “duplicate” my class and rename it slightly, then two icons are shown.