I have a scatter plot with two sources of y data using the same x data (i.e. y1(x) and y2(x) are plotted for the same range of x), and I have a legend to say what each graph is. I want to make a trendline for the first half of y1, but no the whole range, but whenever I use the graph's trendline option, it automatically does it for all of y1. I also tried breaking up y1 into two separate data sources, lets call them y1a and y1b, and used the trendline on just y1a, but then my legend had three labels -- y1a, y1b, and y2 -- and I only want two (y1, y2). Is there any way to make a trendline for just part of y1 without changing the legend?