Because the three tones are generally more integrated, this is a good start for me.
Harmony is generally a three-tone success rate is relatively large, of course, some details need to be modified.
I'm confused by what you want to get.
Do you want a harmony a third above/below the melody?
or
Do you want a three-part harmony and you want to find the third harmony part?
One harmony option is just the notes in the current chord.
The language translations do not help to make things clear.