From what you're describing, I believe the core issue likely lies in the software environment on your daughter’s MacBook or how her Apple Account is configured for iCloud and Find My support. Sharing AirTags requires a few very specific conditions to be met, and any deviation can throw up that frustrating “not eligible” error.
See if the following can help:
- Your daughter’s Mac must be running macOS Sonoma 14.0 or later. The AirTag sharing feature was enhanced around this version. You can check this via: Apple Menu > About This Mac
- Go to System Settings > Apple Account (top left) and confirm that she's signed in with the same Apple Account you're trying to share to. Also, confirm she’s signed into Find My.
- Go to System Settings > [Name] > iCloud > Find My Mac: Make sure it’s On. Then go to: System Settings > Privacy & Security > Location Services: This also should be: On.
- While still in iCloud > Find My, make sure the "Find My network" is enabled—this setting is critical for AirTag functionality.
- For your son's situation, even though you could share with him, the system checks both ends for eligibility each time. Make sure your iPhone is running the latest iOS version, just in case.
Other things to note:
- Some features may not work properly if the Apple Account region doesn't support them. Go to appleid.apple.com, log in, and check her Country/Region matches yours (or supports AirTag sharing).
- If her Apple Account was only recently created or upgraded to include Find My support, it might take a short while (a few hours or even a day) to fully register in Apple’s backend services.
- Try signing her out of iCloud on the Mac, rebooting, and signing in again. Occasionally, this reinitializes the Find My services correctly.
