Hi Andy,
Family table in Creo Parametric is as Configuration in Solidworks and to use that functionality:
1. Create the part as sketch you attached.
2. Select Tools > Family Table
3. Click “Insert a new instances at selected row”, one click will add one row and click on that as per your number of instances (click 8 times will create 8 rows for 8 instances)
4. Now select “Add/Delete the table columns” and set Dimension user *** Item
5. Click on part and select required dimensions to add in Family Table > Ok
6. Replace Asterisk (*) with new values for dimensions and finally “Verify instances of the family”.
Regards,
Mahesh