Chord track = remove notes from chord.

Did a search but didn’t find anything remotely the answer

I have piece of piano midi.
I want to manually enter the chords in the chord track, So it will let me put C maj in. But the chord isn’t a C major. It is a C no 3.

How can I get this into the chord track.

I tried generating the chord track from the midi and that found no chord, since it is a melody.