Hi Joey, Chords played by any accompanying instrument are used to compliment, guide and enhance a melody and can be created from a specific combination of notes from the scale depending on the sound feeling that you’re after (maj, min, diminished, augmented) so while a major triad chord is made of notes 1,3,5 of the scale, minor triad is 1,3-,5 and major 7th chord is 1,3,5,7. Other instruments like a piano, or guitar can play all of the chord notes, but because fiddles only can select 2 notes to create a chord on the fiddle, we choose any two notes from the chord. Our instrument adds it’s own unique flavour, compared to a guitar, banjo, piano chord.
The melody doesn’t just stick with chord (harmonic) notes, it will use notes from the scale, but there will be notes relating to the chord, and sometimes an accidental thrown in for effect. As long as our chords have any note from the chord base we’re using, it’s fine.