Nested radios aren't a function of FF, which you've found out. We can't do the work for you here but you'll need to use some jquery and code some custom radio iniputs. You'll have to go into the "customize HTML" side of the view and then play around with inputs and the hide/show function of jquery: https://www.w3schools.com/jquery/jquery_hide_show.asp

Radio input reference; https://www.w3schools.com/tags/att_input_type_radio.asp

Your code would end up looking something like this in the customize html for the representative field: https://formidableforms.com/knowledgebase/checkboxes-radio-buttons/#kb-display-text-in-between-options

You'll have to wrap the custom radio input around the appropriate "[opt=1] [opt=2]" and then maybe "[opt=3] [opt=4]".

Something like: https://paste2.org/6UpOX9b5