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Our heuristic evaluators all wanted ways to delete and edit tasks, and complained about the lack of safety in task creation. We decided to forego an undo button in favor of an edit mode that would allow users to easily correct mistakes, as well as make changes to tasks that have been on the list for a while. Clicking a button puts the list into edit mode, where users can edit or delete any tasks in the list.
Manage Family Page 
Though we do not expect family members to change often in a typical use case, We included a family management page to add new members and remove members that have left. An edit button was included to allow family members to change their name (or picture in a future implementation) without removing their history of tasks. We decided to use a confirmation dialog to get confirmation before deleting a family member. The efficiency decrease is negligible since this is an uncommon operation in the typical use case, and the extra safety is important because the operation irreversibly deletes that family member's task history.