The main thing we've done here is to make it easier to select groups of notes in FLStudio. With the new notes selected, change the color group selection (which is the pallet of colors in the upper left) and use keyboard shortcut Alt+C (think ALTer + Color).
In order to keep track of the higher octave, let's change the color of the new piano roll notes. This isn't the sort of thing you'd normally do with a piano part, but more likely with an ensemble of strings or brass. Next, I am going to make a copy of the melody and have it play one octave higher, in addition to the melody already in place. Let's begin with a piano melody, I recorded it in FLStudio with my midi keyboard.