I totally feel for you Sorensen!
My daughter started school at 3 (she is 12 now) and ever since then it has been a game of hide and seek with those cartridges- except you will never find an empty one in the trash. Only half empty ones in pockets, drawers, and just about everywhere you would never think of. The occasional leak on clothes is always fun too! When she was younger there was also the occasional stabbing, but as she has gotten older it seems they are more into spraying each other with ink.
Ah, the joys of being a parent that has a child that must use a fountain pen!