Auto Tools, "Time Span Between Dates" - add new variable

It would be possible to create new variable with the number of days in the unfinished month in date difference results? For example %atdatesDaysInCurrentMonth.
It's no problem to count it (%atdatesweeks * 7) + %atdatesdays, but perhaps it would be good to include it in the application for people, who don't need a weeks count.

For example if I count diffrence between 1. Jan 2017 and 31. Jan 2017, now I get result:

0 Years, 0 months, 2 days.

Right result in current version Auto Tools is

0 Years, 0 months, 4 weeks, 2 days.

But I need result 0 Years, 0 months, 30 days.