You don't seem to know how overlapping at offset actually works, so, I'll tell, since you wanted to know.
Offsets correspond to cardinal directions, as X is left and right, and Y is up and down. Negative Y=An object's bottomside, positive Y=object's top (i.e, say Red from Pokemon Red/Blue, that would be his topmost pixels on his hat), positive X=object's right, negative X=object's left.