Hi Mario,
What you’re after isn’t possible in scripting at the moment, you’d need to use the pascal programming module.
Scripting does allow the selection of 1 date to base calculations off, but does not support 2 or more selections. If the range was always a set point after the first date (say 1 year after for example) you could do it with scripts.
For more information on using mouse click points for script calculations please refer to the following article: