Marking planner items complete then incomplete then complete successfully?

[sbattis_groton]

I've built a tool to let students work a bit more directly with their planner items. Problem is, I'm running into a problem toggling planner items complete and incomplete. No matter how I've sliced it, I run out of bites at the apple -- eventually it just gets stuck in a state that I can't change.

Here are the two approaches that I've taken:

First approach.

• Mark an item that has no override complete by creating a new override. Works.
• Mark that item incomplete by updating the existing override. Works.
• Mark that item complete again by updating the existing override. Does not work: the override remains in the incomplete state.

Second approach.

• Mark an item that has no override complete by creating a new override. Works.
• Mark that item incomplete by deleting the existing override. Works.
• Mark that item complete again by creating a new override. Does not work: I get an error that that item has "already been claimed" (by an override that has been deleted).

Is there a third, workable, workflow that I'm somehow missing here?

Thanks!