title: visjs timeline nested events
body: <p>I have a real life requirement for timeline do put product deliveries under shipment. So I basically need nested events where I can drag events (deliveries) under certain shipments or separate them. To get better understanding see this <a href="https://bryntum.com/examples/scheduler-pro/nested-events/" rel="nofollow noreferrer">demo</a> here.
  If I need to schedule shipment, those deliveries will follow. Is there any idea how to proceed or has someone done it before?</p>
  <p><a href="https://i.stack.imgur.com/eQ2xg.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/eQ2xg.png" alt="enter image description here" /></a></p>