Toggling planner items complete, then incomplete, then complete fails… ideas?

[sbattis_groton]

I've built a small tool to let students work more directly with Planner Items in their calendar, but I'm noticing a couple of things that I'm hoping someone else has already encountered and has some tips on working with.

On the face of it, calling the planner overrides API lets me mark planner items as complete or incomplete. But I've noticed that there's a limited amount of toggling back and forth that's available. I've encountered two scenarios:

1. A planner item has no override, so I create one and mark the item complete. Then, when I toggle it incomplete I update the override. Then I mark it complete again by updating the override, but the update doesn't "stick" -- it stays in the incomplete state.
2. A planner item has no override, so I create one and mark the item complete. Then, when I toggle it incomplete I delete the override. Then I mark it complete again by creating a new override, but I get an error that the item has "already been claimed".

Neither of these works terribly well for my purposes. Is there a flow to reliably toggle a planner item complete/incomplete without running out of opportunities to update it?