You should have your own Apple ID. Apple provides several means of sharing items between accounts, both as part of Family Sharing and outside of it (various iCloud sharing features). You can even "transfer" some items by copying. The notable exception to this is ownership of purchased apps and media. Those are permanently associated with the account that was used to purchase them. Most can, however, be shared with other "family" members under Fmaily Sharing for as long as those members are part of the family. In fact this applies to even after somebody leaves a family but you cannot then update them or redownload them if the owner is no longer part of the family.
This support article tells you how to create a new, non-child Apple ID = create an Apple Account. --> How to create a new Apple ID - Apple Support
Merging, splitting or transferring items between Apple accounts (IDs) is for the most part not officially supported. Read the links below for things you may need to do to transfer as much as is possible and to share some others.
Apps and media bought with one ID are permanently associated with that ID. Look into using Family Sharing to continue to be able to use items purchased with one Apple ID with other Apple IDs, and for some data sharing features.
- Family Sharing - What is Family Sharing? - Apple Support
- Set up Family Sharing - Set up Family Sharing - Apple Support
Share folders with iCloud Drive --> Share files and folders in iCloud Drive on iCloud.com - Apple Support
Read How to use Shared Albums in Photos on your iPhone, iPad, and Mac - Apple Support about how to share photos.
If you have signed into the first ID on a device then fortunately when you sign out of that ID, do not erase the device, then sign in with a different ID, it asks you in most cases if you wish to merge the data from the two IDs on your device (toggle the ones you want to on). Say yes and later delete individual items from the other ID that you do not want. Note, in How to save apps and progress on one Appl… - Apple Community a Community Specialist says, "you will not be able to transfer the meta data from one Apple ID to another. Once you switch to another Apple ID the information associated with the old Apple ID will be gone except for physical content on the device like photos and videos." Also turn off storage optimization before doing this. With Optimize Storage, smaller, space-saving photos and videos are kept on your device while all of your original, full-resolution versions are stored in iCloud. Make sure photo optimization is turned off. Manage your photo and video storage - Apple Support
Sign out of iCloud on your iPhone, iPad, iPod touch, Apple TV, or Mac --> Sign out of iCloud on your iPhone, iPad, iPod touch, Apple TV, or Mac - Apple Support
If another Apple ID is signed in you may need to enter the password for that ID to sign out of that ID first.
Click on this link to learn how to 'Sign in with your Apple ID' --> Sign in with your Apple ID - Apple Support
I do not use Apple TV so I can't provide specifics. Here's some support articles that may answer some of your questions:
Subscribe to Apple TV channels in the Apple TV app - Apple Support
Access another family member’s collection --> Library in the Apple TV app - Apple Support
Get Apple TV+ - Apple Support
Multiuser switching
Share Apple TV with multiple users - Apple Support
Manage subscriptions in the Apple TV app - Apple Support
P.S. I see there is a special forum for Apple TV so if you have questions about that you may wish to post them there. https://discussions.apple.com/community/tv-and-home/apple-tv