I works ... but as sprite2 and 3 are tied to sprite.angle/2 (so same value for each) ... sprite begins to move sooner but sprite3 take the same angle/2 a little time after ... when sprite2 stop taking sprite.angle/2 sprite3 continue a little time to move so it works but you must really move slowly to seen any difference as angle range is short between Sprites are allowed moving and not.
THINK i have understand what you want to do (but i'm not sure)!
Try this : replace sprite2.angle formula by sprite2.rotate dt*100 clockwise and the same for sprite3 ! and then change in formulas *100 by other values depending on turn speed wanted. At last, use a variable to see if sprite.angle change when moving mouse and how ... and adjust conditions to only rotate spr2 and spr3 when spr.angle change and in "range" of angles.