PINE64

I am very new to rockpro64. I am looking for charging 3 rockpro64 from a single source. Below are the things I have checked:
1. PoE using switch - I checked the documentation and the home page, but there is no mention of PoE.
2. Charging from USB - I have no idea and tried my best to find it but don't find enough information.
3. Charging from usb3 - I have no idea and tried my best to find it but don't find enough information.

It would be very helpful if someone have any information that can help me.

Simple, just solder your own 12v cables and use a power supply like this.
 
(I make no recommendation about this fleabay vendor, it is purely a link to illustrate the type of PSU I use for my RockPRO64.)