Separate Email notification options

I'm looking to manage mulitple Q&A sites in a muli-site setup. I noticed even though these are separate plugins per site, there is only 1 notification option. Is there anyway to make the notifications site specific?

For example, I have 3 sites.

Global
US
Europe

Is it possible to have users get all GLOBAL questions, but only questions based on their main site membership?

If not, please add this to an enhancement request. Notifications should be site specific, not global. Thanks!