Merging two pandas dataframes while keeping data from the first one in python

Question

I have 2 of the following tables that show x- and y-position as well as the intensity and size of a particle as it moves through frames. I want to compare these two tables and combine them into one. My first table is called green_masked_tracks and my second is red_masked_tracks. I would like to create a table with the following:

I would like to merge on the x, y, and frame columns to combine them into one table, but I still want to keep the extra values from the green table that are not duplicated with the red table. In summary, I have two sets of tracks (red and green), and I want to merge them together where they are similar while keeping the green tracks even if the red is not present. If I use pandas.dataframe.merge(), it removes all of the green tracks that are not duplicated in the red tracks.