I have read the thread this far and can not understand the replies.
If I were there...I would call the children down with a promise of telling them the story of the art they just see as playground equipment. I bet I could get them to stand and honor the memory that it represents before they moved on to another part of the memorial.
I understand your post and your choice of solution is honorable and very pleasing to hear what you would do, but if you were actually there and attempted this honorable solution, I’m afraid the parent(s) who allowed this to happen in the first place would probably accuse you child molestation or trying to lure their kids off...