Sorry, I am totally lost…
I try to read this discussion. (You are there @@)
How to get firebase database sub tag values list
But, it seems my schema template is not suitable for this(?), which I cannot find any similar examples… And I do not want to delete the blocks you made as they are still useful in my mind
Here is the aia. Please help me to change it to firebase. Thank you. 
FilterPostFB.aia (153.2 KB)