Thank you for that.
Just for simplicity let's say we have an iCloud account that is Spouse1, an iCloud account that is Spouse2. There's a third account that we can call Legacy. I do have 3 kids, but they are young and I don't need to complicate things here.
Legacy account was my first and original iTunes account from whenever it started. When I got married, I made Spouse1 and Spouse2 accounts and used the Legacy account for Media & Purchases.
For the longest time, this worked fine. The only annoying thing was that all of the playlists that I made under Spouse1 could be seen by Spouse2 and visa versa. Same with history, etc. But also, when we used to have 1 iTunes subscription if Spouse1 played something, Spouse2 got kicked off, etc.
I recently got Apple One Family through my Verizon plan. This is through Spouse1, and shared with Spouse2. I wanted to migrate Legacy to Spouse1 so I had one less account, but for one reason or another Apple won't allow this migration and refuses to be of help. I have a LOT of purchased movies and TV shows on the Legacy account, not to mention Apps, etc.
So what I did was share my Apple One and add the Legacy account to Family Sharing with Spouse1 and Spouse2. I have 3 kids, but when they eventually get accounts this will keep me at 6 or less which is allowed for a family so it's fine.
The only problem with this setup, is if I use the Legacy account for Media & Purchases I can STILL see everyone's playlists on my phone, iPad, etc. If I login to my own iCloud account for Media & Purchases that handles that issue. But there's something else annoying... when I go to the media library I only see all the purchases if I go into the Legacy library. There's also some purchased movies I can't watch. For example one of the Batman movies, and Christmas Vacation, on the Family Sharing they make me buy the movie again. But when I login to my Legacy account I own them and can watch them.
The whole setup is really messy. It seems what I would love to do is login to my individual iCloud. Then Login to Media & Purchases with the Legacy account. But I wish I could just see my own personal iTunes playlists and history. This is really what I am asking. It's really me saying I want the setup where any movie or show I rent or purchase my whole family can see and use. But the Playlists and listening are unique to each user.
I'll share a further frustration about just using Family Sharing but my own iCloud account. I just got a $50 Apple gift card with a purchase. I want to just add it to my Apple account so when I purchase or rent movies it uses the balance. If I add this to my own iCloud account and not the Legacy account, and I am on my home Apple TV with the Legacy account, I can't purchase stuff for the balance.
It's also kind of annoying that say I keep the Legacy account. You have to have first and last name. It would be nice if you could Nickname an account like that. So on an Apple TV you could just see LEGACY as the name for example. Not "John Doe" or "Doe Family" or something.