I'm impressed you memorized the tells for each chest. yes there is a third scene with Vivian. the reason its hard to find is actually because the game is a bit small at the moment. Vivian is going to have a few chest around the map so that she can be the on the field merchant in some places. she talks about it if you talk to her then leave her dialogue (that's what triggers the chest to appear). there is currently only one you can find out there. its in the cave just right to the lower shadow cave. I'm sure from there you can figure it out from there. ^_^ though the next spot she will have a chest is in lockwood proper and a few other locations going forward.