Trying to fill between chart line

I'm trying to fill the area between two lines on a chart. I'm preparing the msg for the chart like this:

msg.payload = [{
     "series": ["G50","G80"],
     "data":[
        [{"x": 1,"y": chartGain50[0]},{"x": 2,"y":chartGain50[1]},{"x":3,"y":chartGain50[2]},{"x":4,"y":chartGain50[3]},{"x":5,"y":chartGain50[4]}],
        [{"x": 1,"y": chartGain80[0]},{"x": 2,"y":chartGain80[1]},{"x":3,"y":chartGain80[2]},{"x":4,"y":chartGain80[3]},{"x":5,"y":chartGain80[4]}]],
     "labels":["G50","G80"]
}] 

msg.ui_control = {
    "options": {
        "elements":{
            "line":{
                "fill":2
            }
            
        }
    }
}

I tried using "2" for the fill option, but this fills all the way down to the origin instead of between the lines. I've seen that "fill" has a way to specify datasets, but I'm lost as far as how I'd do this using the chart node. I'm kind of new to node red. Any ideas?