How to setup "subscribe by email" plugging for a wp multisite

Hi,

I'm the administrator of a wp multisite with 36 different subsites (based on folders): http:http://www.colegioenriquesoler.com/blogs/blogs.html

It's a school based blogs site and I'd like parents to receive every single post the teacher write just by subscribing to the classroom (the blog) where their children are by using your plugging

I'd like a "subscribe by email" widget located on the right sidebar in every single site (before I buy your plugging I read it was a multisite ready product)

I'd like to know the way to customize the plugging to my convenience in just one single place instead of setting up up to 36 different sites end once the work is done, placing the widget in every site. I guess that's possible, isn't that?

Please I need your support,

Thanks in advance,
C. Llerandi