I am not a Catholic (Get that out of the way first). (BTW did your family sell Iron Ore to Hitler?) The Geneva Convention states quite clearly that the occupying power has a duty to protect civilians in the areas it occupies. A civilian only loses their protection if they actively attack the occupying army. They then become combatants. A 12 year old girl sat at home is not an enemy combatant and neither does she lose the protection of The Geneva Convention, she is still a civilian. An area does not lose its protection under the Geneva Convention. Otherwise the eradication of villages such as Lidice in Czechoslovakia would be seen as legitimate acts of war. As the Geneva Convention was put in place after the Second World War I cannot see how this looophole you are crowing about would be allowed.
Joint Arab List's Odeh: I won't set red lines on resistance to occupation (Haaretz)
from the article: Who is a terrorist?