I was able to steal other objects map keys and make new weapons and armor, at least in the original. Didn't delete the original mapkey (just. Don't know if you're modding the EE or the original. Didn't try it with crafting myself (entered things into treasure table), but my friend got crafting ones to work.
Not entirely sure why you're working in the LSFs. Should be able to do everything with the stat text files. You're defining, say, a piece of armor in armor.txt in the data folder, and then adding a link to a root template in the armor.txt the links folder, and then inputting that into the ItemCombos.txt? Or try adding your object to a treasure table (for say a crate) to see if it works, though you might have to start a new game since treasure tables are set on map load I believe (testing stuff without the editor is obnoxious.)
