I'm not an active user of Apple devices, and researching this for a project. I'm trying to have a group of MP3 players for shared use with a shared library. I wouldn't care if it costed more, but I'd really want the music to be shared. But, I am sure that paying double for double the device sharing isn't a feature. Note these devices will not have wireless (probably going to use like iPod shuffles or something with no Camera/Wi-Fi/Bluetooth, due to the project requirements.
From what I understand, no more than 10 devices where maximum of 5 can be Macs can be associated with an Apple ID. However, I am aware of Family Sharing feature. I'm not sure though if it's possible to have 10 devices associated with one Apple ID, share that iTunes library with another Apple ID and have another 10 devices, and so forth.
If this isn't possible, suggestions on how to get the largest shared music library on multiple devices, while maintaining an easy and automatic way to sync all music? I don't want the manager of these devices to have to drag and drop MP3 files on all devices. I'd prefer plug-n-sync functionality.