What is the correct way to use voltage from multiple sources?
Yes that would work but you will dissipate power due to the diode voltage drop from the hosts. You will also loose some voltage due to the diodes. Best to use schotky diodes to minimize voltage drop and reduce dissipation. Otherwise if you cannot tolerate much voltage drop you should consider the Power Multiplexers that will do very similar voltage multiplexing but with very, very small voltage drops, and also offer current limiting etc.