Pie chart with 'anchored' lines to text box
 

I have a pie chart with a text box (to the upper right). I take one slice and
draw lines from the top and bottom of the outside ends of the slice to
connect to the text box.

Naturally, as the data changes, the slice changes (or the pie slightly
rotates) which requires me to adjust the lines to the box.

Is there a way to have these lines track with the chart?