... I don't think it will stretch that far.
I reckon it would be better to add a small loop in the 5th line above the Y ring.
1: Disassemble the blue 5th line above the Y where the blue line meets the slightly thicker white line at the red ball.
Put an extra loop in where the stopper ball is (it can be a loop or a piece of thicker line with knots at either end). Make sure the ball is still in the 5th line once its assembled.
2: With the 5th line extended, re check that all front lines are even length, if not then simply adjust at the Y point ring under the ball. This adjustment can be made by putting a knot in the thicker white line (you can see this in your second pic), the aim is to make the 5th exactly the same length as the 2 front lines.
3: You might have to lengthen the red safety line that's just above the bar by moving the knot along by one knot, this is incase the entire front line assembly has shifted by a cm or 2. (see 3rd pic)
Lastly, check all the lines with depower rope full and bar against chicken loop.
Hope this helps!
Robbie