How to sum some fields and display it in line chart?

I want to add a line chart displaying three lines: total_data (total_data_bytes), rx (rx_data_bytes), and tx (tx_data_bytes). I use this query below at first:

from(bucket: "wifi")
  |> range(start: v.timeRangeStart, stop: v.timeRangeStop)
  |> filter(fn: (r) => r["_measurement"] == "Client" and r["client_user_name"] =~ /^${userName:regex}$/)
  |> filter(fn: (r) => r._field == "total_data_bytes" or r._field == "rx_data_bytes" or r._field == "tx_data_bytes")
  |> aggregateWindow(every: 1m, fn: mean, createEmpty: false)
  |> pivot(rowKey:["_time"], columnKey: ["_field"], valueColumn: "_value")
  |> drop(columns:["_measurement"])

However, I noticed an issue with this chart where some lines appear identical.

This might be because users can connect to multiple Wi-Fi access points (APs). To address this, probably i have to consider summing the values for identical parameters. For example, if there are four rx_data_bytes lines, you could sum them into a single “Total Rx Data” line.

How to do that? Can someone tell me to build the query? Thank you so much!

probably ask in influxdb forum as it is an influx issue