How to use Event Streaming for consolidation of accounting for multiple child companies

I am looking at the Event Streaming feature that was introduced and I believe it can be used for accounting consolidation for multiple companies.
For example, I have:
(1) Holding company A
(2) Child company B
(3) Child company C

Am I correct in assuming that if I want to do just consolidation in accounting, I just setup the Account DocType in company A to subscribe to both company B and company C, so that it can do the consolidations?
Do I also need to subscribe to all the related Links as well?

Is the Event Streaming done using Redis in the background?