Making update-persistent changes to initrd in CentOS

I am booting a CentOS image via NFS, which requires a custom initramfs from dracut, with some extra modules. I want the kernel to get updated normally, using yum update. This will automatically generate a new initramfs each time the kernel is updated, which doesn't include any of my extra modules. - How/when does yum update generate the new initramfs? - Can the system be configured so that yum update includes my custom modules every time? The goal is to avoid needing yum update + dracut -m "etc" name.img kernel.ver every time we update, since there will be many different system images that we need to maintain.