Filtering that only applies to part of the R-script dataset

Hi. I have two datasets with the same set of columns that should be visualised in the same scatterplot (with smoothed trendlines). I have made a R-script visual where I use ggplot2 to visualise the data as I want to. The 2 datasets include columns x-axis value, y-axis value and date/time value, and I would like to use filters that only applies to dataset 1, so that the curve produced by dataset 2 is "constant". Not sure if this is possible to solve entirely with PBI functions, or if I need to make changes to my datamodel. All help are appreciated. Unfortunatly I can't produce an example for you to look at, due to confidentiallity.