How to make a nested BCD list in bootmgr?

Question

Loaders

I have Win7 with bootmgr on HDD1.
What should be written in the BCD file (the file is located on HDD1) in order to load the BCD list located on HDD2 (on HDD2, the bootloader is the same - bootmgr)?
For example, we boot from HDD1:
HDD1
|
bootmgr
|
BCD
|
bootmenu:
1) Windows 7 (boot OS on HDD1)
2) BCD file on HDD2
If you select the second option in the bootmenu, the following would happen:
HDD2
|
bootmgr
|
BCD
|
bootmenu:
1) Windows 7 (boot OS on HDD2)
2) Windows XP (boot OS on HDD2)
Tried to prescribe in bcdedit path \bootmgr - does not load.
I know it seems that this can be done under grub, but bootmgr is needed.