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How to use a non-contiguous range for diagram?

(Similar to question How do I select non-adjacent ranges in libreoffice calc?, but not identical)

I have a time-based series of data (date&time, value), and I have a diagram showing the data.
The diagram uses the option “first row as legend” (or similar spelling).

Now that the data grows over time, I wanted to start a new diagram for a new year.
So my legend (labels) would still be in row 1, but the data start maybe in row 15.

The idea was to select row 1 in addition to the block of data belonging to the current year.
Say the first year uses $Tabelle1.$A$1:$A$14;$Tabelle1.$E$1:$F$14, and when I use $Tabelle1.$A$15:$A$99;$Tabelle1.$E$15:$F$99 for the next year, unchecking the option “first row as legend”, the labels in the graph are like “column E” and “column F”.

So I’d like to re-check the option, and use something like $Tabelle1.$A$1;$A$15:$A$99;$Tabelle1.$E$1;$E$15:$F$99 for the data, but that syntax is rejected (while it seems allowed in formulas).

Any solutions for that?
I’m using LibreOffice 7.1 at the moment.