Description of problem: 

On a Laptop ASUS n550jx SSD disk (Windows 10 + F28), added a hdcaddy with a SSHD to get more storage.
Installed F28 on SSHD to be able to reorganize data between the disks.

Resulting in F28 on SSD not being reachable as the UEFI boot option was changed to the new SSHD and installation and grub grub2-mkconfig/os-prober did not detect the the F28 installation on the SSD.

Version-Release number of selected component (if applicable):


How reproducible: 
grub grub2-mkconfig/os-prober started to work, unsure why
F28 installation reproducible.


Steps to Reproduce:
1. Install HD(SSHD) in CD/DVD drive space changes ordering /dev/sda -> /dev/sdb
2. Prepare new drive for use with MBR or UEFI boot and use custom layout
Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048            2049   1024 bytes  EF02  BIOS boot partition
   2            4096         1028095   500.0 MiB   EF00  EFI System Partition
   3         1028096         3125247   1024.0 MiB  8300  Boot
   4         3125248       212856831   100.0 GiB   8E00  LVM vg FedoraB
   5       212856832       246411263   16.0 GiB    8200  SwapB
   6       246411264       665841663   200.0 GiB   0700  Windows data

EFI System Partition = ESP

2. Install F28 from USB on SSHD, use custom disc layout and write boot.

3. Boot F28  on SSD (Existing F28)

Actual results:
Can only boot the new installation, existing install is intact with own ESP

Expected results:

To be able to boot existing F28 btrfs based installation.

Additional info:
There is a learning curve here on how installation works and how UEFI can be handled.
I have read #1488204 https://bugzilla.redhat.com/show_bug.cgi?id=1488204  and followed Chris suggestion. 

This is a 2 ESP partion and 2 /boot

A) Copied EFI/fedora to EFI/FedoraSSD. 

B) Added a EFI/FedoraSSD/grub.cfg that boots Windows, Grub SSD, Grub SSHD based on
menuentry 'Grub SSD' {
        load_video
        set gfxpayload=keep
        insmod gzio
        insmod part_gpt
        insmod ext2
#       search --no-floppy --fs-uuid --set=root  <fsuuid for /boot for this dist
ro, will match uuid in its /etc/fstab>
        configfile /grub2/grub.cfg
}


C) changed linking on /etc/grub2.cfg and /etc/grub2-efi.cfg 

D) Updated /etc/grub.d/40_custom with menuentry Grub SSD, Grub SSHD

E) grub2-mkconfig -o /boot/grub2/grub.cfg

F) Booted Setup and added boot UEFI option for FedoraSSD , path to shim on each ESP
 Boot0005* FedoraSSD	HD(1,GPT,xxx/File(EFI\FedoraSSD\SHIMX64.EFI)


n550JX is a HDPI laptop and the console font is super tiny when using the console  and it would be a nice touch if the installer could add a font to grub and a sensible /etc/default/grub note the vconsole.font on GRUB_CMDLINE_LINUX

cat /etc/default/grub
#I managed to get the grub boot screen to scale like this:

# 1) made a new font:
# grub2-mkfont --output=/boot/grub2/LiberationSerif-Regular.pf2 -s 36 -v /usr/share/fonts/liberation/LiberationSerif-Regular.ttf

# 2) made my /boot/default/grub file look like this

GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
# GRUB_CMDLINE_LINUX="rhgb quiet"
GRUB_CMDLINE_LINUX=" vconsole.font=latarcyrheb-sun32 rhgb quiet"
GRUB_DISABLE_RECOVERY="true"

# GRUB_GFXMODE="1440x900x32;1440x900x24;1024x768x32;1024x768x24;auto"
GRUB_GFXMODE=auto
GRUB_GFXPAYLOAD=keep
GRUB_GFXPAYLOAD_LINUX=keep
GRUB_FONT=/boot/grub2/LiberationSerif-Regular.pf2
GRUB_GFXPAYLOAD_LINUX=keep
GRUB_TERMINAL=gfxterm

# 3) Deployed the change to my EFI grub config:
# grub2-mkconfig -o /boot/grub2/grub.cfg