Allow the use of both Fixed and Non-fixed values when setting due date policy
Faculty at our institution are allowed to check out materials until the end of summer. They are also used to renewing their materials before the end of summer so they are extended to the end of next summer. Currently the recurrence of End of Summer will change the End of Summer date to the same date next year is the same time that faculty materials are due. They cannot renew them before the current End of Summer.
I propose the ability in Advanced Policies to set due dates based on how many days before or after a certain event.
For example, I would like to set the End of Summer to 8/18 and have it recur yearly, but also create an advanced policy that sets due dates to something like "2 days after End of Summer". This way we can set up automatic renewals to run during the new End of Summer event without manual intervention.