Can more than 10 devices be associated with one Apple iTunes account? 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.
More than 10 Apple devices can not be associated to a single Apple ID.

A single Apple ID can be used to log into upto a maximum of 10 Apple devices where no more than 5 of them can be macOS devices.

A Family sharing group can consist of upto 5 members (apart from the organizer). Each of the 5 members setup their devices using their own Apple ID.

The original limit of being able to use an Apple ID on upto a maximum of 10 Apple devices apply to each family member.