If I claim the existing backup on my disk, will these be loaded onto my new iMac
Should the computer claim the existing backups on the disc "g drive"
If the computer does claim the existing backup what is the effect on my new iMac.....
Question marked as
If you claim the existing backup, then your new Mac will own that backup and the ability to restore files and data from it. The Mac will also continue to backup to that drive normally. There is no other real effect on your new Mac.
However, you will be unable to continue to use that backup with the old Mac. That's not a problem if you will no longer use that old Mac.
For more info, please see: If your new Mac inherits your backup history - Apple Support