Normally, *GRUB2* is preset to boot multiple operating systems during the Fedora installation process. If you can, it is advisable to install non-Linux operating systems first. Then, during the installation process, all those operating systems and their locations will be discovered and properly set.
Adding other records into the *GRUB2* menu only means to run `grub2-mkconfig` command to regenerate the configuration files. During this process, all operating systems known to the system will be added into the configuration. By reinstalling *GRUB2*, this configuration will be used for further boots.
* When problems appear, see the link:https://www.gnu.org/software/grub/manual/grub/grub.html#Multi_002dboot-manual-config[GRUB manual] to solve issues with booting secondary operating systems.