Father\'s/Parent\'s maiden name

14:48 Aug 10, 2018 

I'm afraid your empirical approach and the conclusion to which it has lead you are fallacious!
There is no way that 'maiden name' in EN can mean 'nom de famille' — it is simply never used that way.
So in your example, either the father and mother are related (siblings, or cousins in the male line) — or the mother simply chose not to use her maiden name.
Obviously, as the father doesn't have a 'maiden' name, it will be the same as his surname — though I suspect the clerk simply got it wrong, and should have left 'maiden name' blank for the father; they seem to have been equally incompetent, in failing to register the mother's maiden name.

By the way, we would normally do everything possible to avoid a double possessive as you say — for example, here, "name of child's father".

12:35 Aug 10, 2018 

Thank you very much for the input. I decided to stick to "Nom de famille" for the following illustrative reason.
The child's father's name is 1 2 3 (oh, the double possession is awkward :))
Father's maiden name is 3 (the 3 above)
The child's mother's name is 1 2 3 (with 3 being the same as that of the father).
My conclusion is that "maiden name" is this context ONLY" means "Nom de famille).

12:25 Aug 10, 2018 

Good point!
However, in most instances, 'maiden name' seeks to elicit 'birth name' — which is usually what is needed in order to be able to trace the person back to their parents.
If the person has been known by any other name in between (e.g. the deed poll situation you mention), then (where important) forms often ask for 'any other names by which the person has been known'.
Indeed, we tend to treat it this way in EN anyway, since instead of saying 'maiden name' in running text, we often use 'née'.

12:13 Aug 10, 2018 

Note that somebody's "maiden name" might not be the same as their "birth name", for instance if the surname was changed by deed poll or otherwise while they were still unmarried.

11:46 Aug 10, 2018 

I think you are just reading it wrongly: they only intended it to be 'maiden name (if applicable)' — though in today's politically correct world, in the event of 2 guys marrying, one may or may not take the name of the other; indeed, even in M/F couples, it is extremely rare but not unheard of for the man to take the wife's name instead (legality?)

'name at birth' is a more inclusive way of covering all bases.

10:09 Aug 10, 2018 

the Father's parents