See the code in item 5 of Paired Folders - Nav Lock issues - #5 by jimerb
@showif:=return Len(Resolve(source, "p")) > 0
function OnClick(clickData)
{
var cmd = clickData.func.command;
// See https://resource.dopus.com/t/paired-folders-are-they-already-functional/46101/5
cmd.runcommand("Go OPENINDUAL NEWTAB=findexisting PATH {sourcepath|pair}");
}
A button will appear only when you open a folder that is part of a paired folder. You can then decide to open the pair or not. Click on the button and it will open the other half of the pair in the other side of a dual lister. Kudos to @aussieboykie