I'm charting a progress (Y axis) against dynamic range of dates (X axis).

I've inserted some text comments in a text box (e.g. "Delay due to water
management issue") and used arrows to indicate the region on the chart where
they apply. Now I want to change the Max date (X axis) as the project is
taking longer than expected, but doing so changes the location of these
arrows and hence they relate to wrong regions.

How do I link these arrows (and text box, which I think, can be grouped
together to form one entity) to a specific region so that, even with new date
range, the arrows still show the regions correctly.

Thanks in advance.

RL