There was a script I used in Maya, called Snap Animation by Aaron Koressel, what it did was "Takes current selection of keys and offsets it's values so that it lines up with the neighboring key. Very useful for pasting/rearranging animation and keeping your animation relative to it's neighbor. Or snap a key into a hold and have the neighboring animation offset appropriately."
So I could animate, let's say, a character breathing, then paste this animation into another scene with this character, create a pose in a frame before the breathing animation and then select all of the keyframes except the first one (the one with the new pose), and snap that first breathing key to the new pose, and that would automatically also change the other keys by the same amount, making so that I would have the character now in the breathing in the new pose.
Is there a way to snap a key to the previous one like that on Blender?