Maybe an embedded macro would pass, but I don't think I've ever used them so who knows? Besides, can't all of this be avoided by making the task list a subform? Then you can append/edit tasks in the subform. I agree - flag the task as completed instead. Even better, give it "Complete" as a task status and have a LastUpdate Date field. You can only date stamp the last task status that way. If you need to maintain task status history you need a table for that.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.