Remind me to grade by... - Relative dates

Hello! 

I am wondering if it would be possible in Assignment plugin to have relevant dates for the Remind me to grade by...

This date appears in Calendar and Course overview block of the teachers, reminding them to assess students' work. 

But in MEC for example we cannot use this cool feature because there are no due dates for the Assignments, as the courses are offered all the time.

It would be amazing though if we could set the Assignment with a Remind me to grade by... using a relevant to the submission date, and say for example remind me to grade in 1 week from submission.

What do you think?

Anna