Automation to notify the owner of a dependent task

Hi all!

Question 1:
I am curious if there is a way to set an automation ( in a subitems list ) to notify the person assigned to a dependent task when the first task in the dependency line is completed?

For example:

Task one no dependencies
Task two dependent on task one
Task three dependent on task two and so on and so on

I would like to automatically notify the owner of task two when task one is marked completed.

Question 2:
I would also like to ask if there is a way to create automations specific to groups in a board?
All help is appreciated!