If I get this right, you could boot (Wimboot) Windows 7 but you stop because the BCDBOOT cannot make a "correct" BCD entry for it?
A possible solution is here (whether you will like it or not is another thing):
http://reboot.pro/to...ch-using-linux/
It is not Wimboot Windows 7, but Boot with Windows 7 x64
Then Mount Win10x64 VHD as Drive N: and try to make new entry into the VHD internal BCD e.g. N:\Boot\BCD
When I use W10x64 version of bcdboot and command as given Or W7 bcdboot without /f ALL, it all fails, wheras I can use such command with succes in Win10x64 or Win8/8.1OS
bcdboot.exe N:\Windows /s N: /f ALL
I tried your suggestion to use bcdedit for that purpose to create new entry in BCD
Using Windows 7 x64 OS Or Win 10 x64 OS then I can create such entry in the N:\Boot\BCD but it is not correct
bcdedit /store N:\Boot\BCD /create /d W10x64_NL_7-VHD /application osloader
gives guid {513f748d-4e64-11e9-b210-3052cb53659e}
bcdedit /store N:\Boot\BCD /set {513f748d-4e64-11e9-b210-3052cb53659e} device partition=N:
bcdedit /store N:\Boot\BCD /set {513f748d-4e64-11e9-b210-3052cb53659e} path \Windows\system32\winload.exe
bcdedit /store N:\Boot\BCD /set {513f748d-4e64-11e9-b210-3052cb53659e} osdevice partition=N:
bcdedit /store N:\Boot\BCD /set {513f748d-4e64-11e9-b210-3052cb53659e} systemroot \Windows
bcdedit /store N:\Boot\BCD /displayorder {513f748d-4e64-11e9-b210-3052cb53659e} /addlast
bcdedit /store N:\Boot\BCD /default {513f748d-4e64-11e9-b210-3052cb53659e}
The problem is that the generated entry refers to the VHD instead of to the mounted partition.
Strange enough enum and enum /v show total different info for the last entry
C:\Windows\system32>bcdedit /store N:\Boot\BCD /enum
id {default}
device partition=N:
path \Windows\system32\winload.exe
description W10x64_NL_7-VHD
osdevice partition=N:
systemroot \Windows
C:\Windows\system32>bcdedit /store N:\Boot\BCD /enum /v
id {513f748d-4e64-11e9-b210-3052cb53659e}
device vhd=[M:]\W10x64_NL_2.vhd,locate=custom:12000002
path \Windows\system32\winload.exe
description W10x64_NL_7-VHD
osdevice vhd=[M:]\W10x64_NL_2.vhd,locate=custom:22000002
systemroot \Windows
Do you you know the commands to get the correct entry for BCD inside VHD booting Windows of that VHD ?
I need probably something else than device partition=N: but what code will give succes ?