*sigh* sorry for not speaking clearly about this. Let me try one last time, been a bit stressed out again. Nowhere did I mean to imply switching accounts was mandatory to achieve what is wanted here on the AppleTV. And I still have no clue what Movies Anywhere is, sorry.

Family Sharing is the name Apple uses for sharing within Families while allowing every individual their own seperation if they wish.

Family Sharing and iTunesIt lets you bind multiple iTunes accounts together, but the bindings can be broken later. Say your child wants some seperation when they go off to college for example and they want to start paying their own way. Setting this up is useful so that you can share content between folks individual devices as a Family. You can download apps your wife may have bought/downloaded before you switched to iPhone, etc... Again, this only applies to content bought directly from Apple, be it an individual music track, a TV episode, or a movie in the iTunes Store. As well as books, apps, etc in the other stores Apple runs.

Family Sharing and iCloud Accounts. Lets you bind multiple iCloud accounts together for paying one price, and having shared and split private spaces. 2TB of storage for example applies to everyone’s individual iCloud Photo Libraries, and creates an automatic shared “Family” album which can be used to share photos to everyone on the plan. For the AppleTV, switching the iCloud account switches who’s photo library, personal music library, and other things are by default accessible on the TV.app home screen of the AppleTV.

(Similar to switching between multiple “profiles” on a single Netflix billing account with all of Netflix content available to all profiles, or one profile being limited to “kids only”. Apple has a specific under 13 account that can be set up under Family Sharing that helps let your kid have their own devices with only their kid friendly content on it).

*edit* I should add, there’s no cost for this. Only that Family Sharing also applies to the optional paid for services of iCloud too. Prior to my partner and I joining our accounts, they paid for a $0.99/monthly 200MB a month plan that grew to 20GB, and I was on a tier above that recently grew to 1TB or something. When we merged, we simply paid similar to hit 2TB for all of our online iCloud space.