can't you create an `IMAGE_PATH` constant in your backend model, that's has `FRONTEND_FILES_PATH . '/' . FrontendPartnersModel::IMAGE_PATH` as a value, but without using the frontend model constant? Throughout your backend you use this `FRONTEND_FILES_PATH . '/' . FrontendPartnersModel::IMAGE_PATH` a lot, so better extract it to a single constant, or even a method `BackendPartnersModel::getImagePath()`