Auto assign assets to site when assets are created ?

Auto assign assets to site when assets are created ?

We want technicians to manage their respective sites without seeing each other.

In assetexplorer there is a option "Auto Site Allocation"

Is there anyway to do it on SDP Cloud? 

Can i use trigger and custom function to do it ? but i can't understand custom fuctions. 

Is there any example for custom fuctions ? Thanks.