This is getting too complex for me to grasp. 🙂 There are just so many possibilities and you will have to tailor them to meet just what you want. Just some thoughts:
Do you have any iTunes Store purchases? You can share some with Family Sharing.
If you are using Match each user will have to have a library to Match.
Multiple iTunes libraries on a single computer can share media with some limitations (you had better agree before you rename, delete, or add any tracks) to save drive space. Multiple user situations and libraries is a large topic unto itself.
Home Sharing between multiple computers.
Sharing is a lot easier for home CD rips than Store purchases where transfer is somewhat controlled by belonging to an AppleID.
Share your iTunes library over your home network - Apple Support - https://support.apple.com/en-us/HT201779 - about Music Sharing and Home Sharing
Home Sharing Support page - http://www.apple.com/support/homesharing/
iTunes 12 for Mac: Use Home Sharing to import items from another iTunes library - https://support.apple.com/kb/PH19614
iTunes: Setting up Home Sharing on your computer - http://support.apple.com/kb/HT4620
Understanding Home Sharing - http://support.apple.com/kb/HT3819
Family Sharing - http://support.apple.com/kb/HT201060 - "Family Sharing makes it easy for up to six people in your family to share each other’s iTunes, iBooks, and App Store purchases without sharing accounts. Pay for family purchases with the same credit card and approve kids’ spending right from a parent’s device. And share photos, a family calendar, and more to help keep everyone connected."
Sharing purchased content with Family Sharing - http://support.apple.com/HT201085 - "With Family Sharing, family members get immediate access to each others’ music, movies, TV shows, books, and apps, and can download them to their own devices any time they like.*" "* Not all content and content types are available in all countries. All family members must use the same iTunes Store country or region. Music, movies, TV shows, and books can be downloaded on up to 10 devices per account, five of which can be computers. Apps can be downloaded to any devices the family member owns or controls.