Tasks under multiple groups

Hello,
Is there a way to associate one task with multiple groups of tasks? For example, let’s say I have the following tasks:

  • task A
  • task B
  • task C
  • task D

I have two groups:

  • group 1
  • group 2

I’d like to create this grouping:

  • group 1
    • task A
    • task D
  • group 2
    • task A
    • task B
    • task C
    • task D

How can I do this with Omniplan 2.4 (OSX)?
Thanks.