Member registration

Phil,
https://premium.wpmudev.org/forums/topic/member-roles-across-buddypress-multi-site

I found this thread and wasn't sure how to best respond.

First let me say thank you for the clarification and the visual aid.

So I am testing this stuff also. So I have to be logged into network to even see the new member who has no roles and isn't assigned to any website.
1) What is the mental work flow that is involved in assigning them a basic role on the main website.

Can one of the plugins activate this work flow like membership ? upgrade a leve?

2) How can I automate that with some base settings or do I need to do that each time someone signs up?