Or, you can use two ORing mosfet instead of forward diodes..
1) higher current capability (provided that you use power fets with low "on-resistance"),
and also, no need to increase the output voltages of the two supplies..
2) smaller compared to mechanical relays (if you use mosfets with small packages like "power so-8")
1) additional circuit (and also bias voltage) for turning-on the two ORing fets..