Joining two data series (hist + new) into one data set from Flux query

I had issues when converting influxDB from version 1 to 2 and lost the correct format in transition which required me to download and convert the historical value into CSV format. I finally managed to download the data back to InfluxDB2 (Flux used as Grafana query database). To combine the Historical data and the new Live data i combine the queries into same dashboard such as.

As noted I have now 4 different time series. I would like to clear up data and have only 2 data sets as the historical and Live dataseries are the same.
I used the transformations ; reduce row ( ie- combining the series) and the hiding the rest with Filter by name.

Results exactly as I wished. But then noticed that if I select a time frame that does not have this inter lapping time frames ( ie. all dataset are available in the 30d selection but if would only look for the last 7d I would not get anymore correctly formatted output as it seems that transformation has to have all data fields present.

is there any “more correct” way to combine the historical data and the new live data so I would only have the 2 data series going through different time selections ?

Thank you for any help.