You can't make a bond in both the transformer and the panel on a SDS. You only do it at one location. No matter where you make the bond, there has to be a path from the transformer case to XO. If you bond at the transformer, the path is direct from the case to XO. If you bond at the panel, the path from the case is via the equipment bonding jumper to the panel. In either case an equipment bonding jumper is required between the transformer and the panel.
Don
