Graphpad Prism: custom legend?

F

Hey there folks,

hope someonw can help me.
I'm currently using Prism for some graphs, and I needed to include data of a second sheet into the first, but using parts of the data of the first. To point that out, I manually changed the symbols of the data used in both calculations. Now I need to represent that in the legend. How can I do that? I can't edit or include anything to it that's not represented by a whole data set, as far as I can see it.

Thanks in advance!

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