In the construction script, you need to get the location of the cube (both cube A, and cube B)
Then, in Tick for the cube B, you get the Actor World Location of A, subtract out the position for A you got on construct, multiply by two, then add the position you got for B on construct, and make that the new position of B.
The end result will be that B movement relative to where it spawned will be 2x A movement relative to where it spawned.
And instead of “subtract,” you might want to capture the full transform on construct, transform A by inverse of captured transform, then transform the result by B captured transform, and make that the B transform. That way, you could echo rotation and scale, too.