Sorry, I was out and couldn’t answer well on the phone, I found a solution for you 
.
Since each firebase.dataChanged returns all the data from the bucket, you can simply save the list, use add item to list, and send back the entire node with the added data.
Plus, there are no annoying double quotation marks.
use a Web.putText
It’s not ideal from a technical point of view, but it works well!! 
wisdom