component dialog: how to auto-show/hide/retrieve fields (based on dropdown list selection. example inside)

Scenario.

• I can have 1 or more primary tasks.
• and 1 primary task can have 1 or more secondary tasks.
• Both primary and secondary tasks are multifield (granite/ui/components/coral/foundation/form/multifield).

Screenshot explanation:

• The primary task dropdown list has been entered via the "Primary Task" tab. I entered 4  values into it. (screenshot1)
• On the secondary tab, I need to select 1 of the options from the "Primary tasks" that I entered.
• If there are no "secondary tasks" associated with the selected "primary task", something like in screenshot2 is displayed. I will then manually enter records for it I choose to do so.
• If there are "secondary tasks" associated with the selected "primary task", something like in screenshot3 will be displayed. The records will be displayed below and I should still be able to add more records.

Thanks heaps for the assistance.