I realize there have been a few questions which dance around the solution I am after but I believe I am looking for something specific.
This is actually a two part question:
1) My goal is to have wordpress operate in network (multi-site) mode and I am trying to figure out a way to essentially "group" specific sites together. I am aware of the "Multi-Network" plugin but I question if this is the best approach for this? The key here is to allow specific users to add/edit the sites within their own sub-network.
2) This is the key question of this post... I would like to know the best approach which would allow me to essentially query posts from within this "sub-network" of sites. So, for example if there are 10 sites within this sub-network and each of them created posts within a custom post type called "news" then I would like the ability to display for example the 10 most recently published posts from this collection of 10 sites.
NOTE: I need the ability of being of being able to create multiply sub-networks which in turn means that a query of the latest published "news" can only display posts from those belonging to the correct group.
Finally - I do realize solutions exist for doing stuff like this but I am looking for the best approach on both cases which require the LEAST amount of database load/queries. I would also very much like to do this through code in my functions.php file rather than installing plugins which create extra bloat.
I am very open to any suggestions and appreciate any response.