Grub Multiboot 2 Partition

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I have a USB MultiBoot that boot different operating systems. I use only one FAT32 partition to have compatibility even with UEFI Now I wanted to split into 2 partitions, one NTFS and one FAT32 The problem is that I can not direct the startup for the installation of operating systems

For example, I use this command line in Grub2:

Code:

if [ "${grub_platform}" == "efi" ]; then
   if [ "${grub_cpu}" == "x86_64" ]; then
   menuentry "Windows 7 SP1 AIO (x64)" --class w7 {
       insmod part_msdos
       insmod chain
       chainloader /efi/bmgr/W7X/BMGRx64.efi
   }
   fi
fi
if [ "${grub_platform}" == "pc" ]; then
   menuentry "Windows 7 SP1 AIO (x86)" --class w7 {
       search --file /boot/bmgr/W7 --set=root
       insmod ntldr
       ntldr /boot/bmgr/W7
   }
   menuentry "Windows 7 SP1 AIO (x64)" --class w7 {
       search --file /boot/bmgr/W7X --set=root
       insmod ntldr
       ntldr /boot/bmgr/W7X
   }
fi

instead in Grub4dos simply

Code:

title Windows 7 SP1 AIO (x86)
chainloader /boot/bmgr/W7

Now if I had to tell him what partition needs to start, what should I add ?! I tried with the "set root=(hd0,1)" but I can not ... I also tried to put NTFS / FAT32 or interted but nothing

Thank you