EasyBCD is just a tool to manage the contents of the BCD store which MS bootmgr uses. It's not active during a boot, only when you start it on a running OS.
The MS bootmgr is 100% responsible for what happens during a boot of your PC and like its predecessor, XP's NTLDR, it makes absolutely no provision for modifying the "hide" bit in the MBR. It will respect it if it finds it, but it does not alter its status to enable you to let you switch between two mutually invisible OSs in the way you want.
You can however simply boot each SSD by altering the BIOS HDD priority sequence at power up (or with a function key temporary override) and when either OS is running, use Disk Management to remove the Windows drive letters for the two partitions on the other SSD. This makes them invisible to File Explorer and thus immune from accidental use.
Drive letters are not "real", only virtual labels stored in the registry of the running OS, so there can be no conflict between apparently having two C and two D drives. The running SSD will allocate unique letters to the other SSD's partitions using the first two unallocated letters in its own map at PnP detection during the boot phase.
They're the letters you will subsequent remove using Disk Management.
Windows PnP will use your "blank" letter assignment on all subsequent boots rather than assigning new ones.
There used to be a Neosmart "Windowized" version of grub which was renamed to "bootmgr" to trick Windows into using it.
It was designed to solve the problem of XP destroying the restore points of Vista if it could see them, but is now no longer necessary for that purpose and has slid into the dustbin of time.
It's what brought me here 16 years ago.
Further to my "How to triple boot...." thread, here's a further mod to the HnS menu.lst to add a Linux system into the mix, all controlled through the single HnS boot menu, with both Vista and W7's system restore points protected from corruption by XP. Subject to the same conditions mentioned...
neosmart.net
