Just keep in mind that not all Khukuri were 'issued'. If the Gurkha carried his own personal Khukuri, then it won't have the MOD stamp on it. There were plenty of issued and unissued Khukuri in use in the earlier wars. Not so much these days though. So stamp or no stamp, it won't detract from the family history as it applies to your blade. You should try to get as much information about that gear as you can now, before it is lost altogether.
Mick