Deltarune Chapter 4 - All organ piano secret songs

These are all the songs you can play on this piano and get a comment from your party members. I saw the list of these straight from the code, so I believe it's complete, but please let me know if you find any more!

edit: oh god this is actually getting views. so I should say thanks to KockaAdmiralac for datamining the list of songs :D also pssst while I have you. the deltarune wiki moved off of fandom, it's on deltarune.wiki/ now, go there for your info please it's way more complete and does not have ads

There's 3 songs (edit: now two) that I don't know what they actually are... any help figuring them out is appreciated ^^;

0:00 Memory
0:14 Your Best Friend
0:25 Annoying song? (don't know what this is)
0:43 The Legend
0:54 Don't Forget (but slightly off for some reason)
1:16 Lost Girl
1:29 Rouxls
1:43 Gerson...? (Spear of Justice maybe)
1:53 Heartache
2:06 Messing around (one I don't know, Chopsticks, Heart And Soul)
2:41 Undertale
2:52 Dark Sanctuary
3:10 Correct melody, without octave switch
4:00 Correct melody
5:05 Megalovania