Yes, you can use SetOwnership (or ClearOwnership, w/ CS 1.2) to mark it un-stolen - and IsOwner to identify whether you already own the item, and ShowQuestItems to keep the player from altering (seeing) their quest items, etc. Like I said, I think I have the rest of it figured out, it's just getting a menu worked up to show the player that troubles me.
Hardcoded, you say? Unfortunate. And unfortunately I don't know what an xml is, other than a file extension. ...Peruses Wikipedia article... A markup language? That doesn't sound so bad by itself. I'll have a look at that, then, probably a few days from now. But I will assuredly be back with more questions when I do. One that can be answered right now, I think, is this: So if I get a new menu, uh, formatted in xml, then would I be able to tell the game to open this new type of menu with a command 'Begin MenuMode NNNN', NNNN some numeric identifier outside the already used range 1001-1051 that I assigned to my new menu? And also, is it possible to assign the repair hammer menu "backdrop", the "skin" that forms the metal frame and parchment background, to another menu, or is there a naming convention that prevents two menus from sharing the same backdrop resource?