Content Sharing Logistics Question

Question about content sharing logistics for the following scenario:

Lets say a campaign has 3 people: DM, Player A, and Player B.

DM: No subscription. 
Player A: No subscription. But has books X,Y, and Z.
Player B: Master tier subscription that can enable content sharing but no books.

If Player B enables content sharing for a campaign, does the DM and Player B get access to Players A's books?
Or does Player A need the Master tier subscription for this to work?

They'll all get the books. 

The only issue is that only characters in the campaign where the sharing is active will be able to use the associated character builder options, which makes it a bit awkward - but that's true regardless of who has the sub etc.

So long as someone has the books, and someone has the sub with content sharing active the campaign (doesn't have to be the same person), then those books will shared with everyone.

Awesome! - Thanks a lot for the info!