Custom field checkboxes with owner input

Hi there

We want a todo/task list in our tickets. This could be implemented with custom field checklists. However, we could not find a way to let the owner add more tasks.

Basically, we like to have a set of tasks (checkboxes) assigned to a ticket and be able to customize the list further for each ticket individually.

Before we jump into coding something ourselves, does anyone know of a similar solution?

Thanks Andy