A Microsoft file hosting and synchronization service.
Hello, thank you for reaching out to Microsoft Q&A.
If you have two separate Microsoft accounts signed in on OneDrive, your files will not be shared with another account or member, even if they are part of an Office 365 Family group/subscription.
Each member in the family group has a separate email inbox, calendar, OneNote, and OneDrive storage. If you choose to share a folder with another member, they will be able to view those files.
Since you already said that all the desktop files are set to private and not shared, it is possible that your account may be signed in on the second laptop.
- Open OneDrive on the Second Laptop. (Right-click the OneDrive icon on the taskbar and select Settings)
- Then, go to the Accounts section.
- If you see your account is signed in there, just click 'Unlink this PC'.
This should remove the sync on the second laptop.
Let me know if you still need more help.