Variable Action Notification Recipients

I am making a notification effect action where an automation triggers the send of the notification. The challenge is, I need to make the recipient list variable based off of object properties. I solved for this in the past by making the group inbox emails they gave me their own users, which was pretty straightforward although cumbersome to store those User ID values in an override block property in the action form. However, now they want me to also have it variably send to groups that have users within them, too, that aren’t group inboxes I can just make their own users. I.e. GroupA has Kelsey, Michael, and Shane, so if object property = A, send to all people under Group A as well as a group inbox called Amaintenance@client.com stored as its own user, a-maintenance. How would I go about doing this?

Going to go ahead and make nested recipient groups in user settings instead that include those user IDs and other groups, and then use those group IDs in the override property block