You can share a folder on a Mac that other Mac computers on your network can use as a destination for Time Machine backups.
- On the Mac you want to use as a Time Machine backup destination, choose Apple menu > System Settings, click General in the sidebar, then click Sharing.
- Turn on File Sharing.
- Click Options, then make sure “Share files and folders using SMB” is turned on.
- Click Done.
- Click at the bottom of the Shared Folders list.
- Navigate to and select the folder you want to use for sharing, then click Add.
- Control-click the name of the folder, then choose Advanced Options.
- Turn on “Share as a Time Machine backup destination.”
- If desired, turn on “Limit backups to,” then enter a size.
- Click OK.