 Before the switch-around, objects (1) and (2) temporarily coincide, in the place where you keep the bicycle your uncle gave you, and objects (3) and (4) temporarily coincide, in the place where you keep the bicycle your aunt gave you. After the switch-around, objects (1) and (3) coincide, and objects (2) and (4) coincide. When we initially talked about ‘the bicycle your uncle gave you’, there was no fact of the matter as to whether we were talking about (1) or (2). And (1) and (2) end up in different places after the switch-around, which is why we don’t know what to say about the final location of the bicycle your uncle gave you.