Best way to develop a song once I have a melody?

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I don't really know what I'm asking for here - new to LMMS and this kind of program in general. This is the deal... I have a simple flute melody, and now I want to add other instruments to the tune. I would like to be able to play the melody and see the notes as I attempt to harmonize the other instruments with it. The only way I can see to this is to clone the track in general and apply it to another instrument, but that just plays the same tune with another instrument, it does not help me to harmonize the instrument with my melody.

So is there a way to play my melody and see the notes while adding notes for another instrument in the Piano Roll? What is the typical way a musician using LMMS handles this issue? I mean they probably don't copy the melody of their song 100 times for 100 instruments, so how to they build their song off their original melody? Is there a tutorial, besides what is already out there (I have ALL YouTube tutorials) that shows, with narration, how someone makes their music with LMMS? If not would someone be willing to do this? Perhaps I am simply not understanding the right way to use this sort of program. I would like to learn the generally accepted correct way.

I really appreciate your help!
- Deathbliss
There really is no one right way. You have to know some music theory. What key is the song in? Once you know that, you can figure out what chords go well with your melody. Most instrumentation apart from the melody is just chords and "broken" chords.