This highly experimental package can be used to add NFSS-declarations of combo fonts to LuaLaTeX documents. This package may disappear without notice, e.g. if luaotfload changes in a way so that it no longer works, or if LuaTeX changes, or if fontspec itself includes the code. It is also possible that the package’s syntax and commands may change in an incompatible way. So if you use it in a production environment: You have been warned.