If you want legal advice, seek out a lawyer...but remember there are always two sides to be argued in court. Since neither David nor I are lawyers, I'll pretend to take the defense in your aintevernevergonnahappen lawsuit.

Definition of melody

1 : a sweet or agreeable succession or arrangement of sounds.
2 : a rhythmic succession of single tones organized as an aesthetic whole a hummable melody

If you did not write the melody for your piece, then who did?

Is your melody substantially similar to the melody recognized from the Lennon-McCartney song? I'd argue strongly that not only is it not substantially similar to that melody, it is by design as substantially UNsimilar as was possible with the method by which it was derived.

Is it copied? Again, such elements that may be similar to the Lennon-McCartney song are not by definition melody at all.

Does the prosecution wish to claim that the lengths of melodic notes were created by his clients who now owns them for life plus 70 years? Henceforth is nobody allowed to use the same sequence of note durations as he/they did?

Since the Mssrs Lennon and/or McCartney did not and cannot claim to have written the melody, any portion of the melody, or any "melodious" (by definition) aspect of your piece, the arguments of the Plaintiff are unsupported and unsupportable. Ipso facto, corpus delecti.

Side note to the defendant. This is a technical, not a legal or moral or philosophical question. How were the chords derived by your software, if indeed they were? Negative harmony? Harmonization of the new melody? Something else?

Now...philosophically, you face the same sort of conundrum I face when people ask me if I wrote the music for a BIAB-based piece. My answers, in ascending level of detail required to get the deer-in-the-headlights look or a faux-understanding nod are:

1. I programmed the music.
2. I made up the chord arrangement.
3. I made up the chord arrangement and a few other things and used software to create the various parts.
4. I made up the chord arrangement and a few other things and used a program call Band in a box and a DAW to create (most) of what you hear.
5. Come over and I'll show you how I do it. But, remember, I'm married.

I don't tell anybody I "wrote" the music, though I do take credit for the end results. Since neither publishing nor intellectual property "laws" have kept pace, I fill in the forms as required. Without explanation.

As your fake attorney, I'm fine with any explanation you give. As Noel so well pointed out, you used a software short-cut to eliminate the relative drudgery of a time-honored and noble pursuit of melody. There's no shame in it. Most people still think "we" are scratching down notes on staff paper. Let them be as ignorant as they choose to be. Just don't mislead them should they ask.

BIAB 2021 Audiophile. Windows 10 64bit. Songwriter, lyricist, composer(?) loving all styles. Some pre-BIAB music from Farfetched Tangmo Band's first CD. https://alonetone.com/tangmo/playlists/close-to-the-ground