This one wants the Galilean Jesus to start the day in a different place (sunrise) in stead of where the Judean Jews started it (sunset). That is supposed to reconcile the accounts. That is a simple explanation if one is after an explanation, which you are not.
versebyversecommentary.com
That creates a 3rd story different for the other 2. That is a problem.
I will take a simple explanation, but that is not simple. You are now saying one account is wrong.
So you repeat the speculation of Bart Ehrman and that is supposed to prove your case.
Well first Ehrman is a PhD in NT history, is reading the original Greek and studies this with the thought in mind that it's the true, accurate word of God and nothing is going to change his faith. So he wasn't looking to discredit the Gospels. He sees a discrepancy. But the Gospels prove the case. You already tried to change one Gospel, which also proves the case.
As far as I can see the synoptics have Jesus die on the Friday and John's gospel does also.
So it is just a matter of finding why Jesus and His disciples might have eaten the passover a day early.
More than one possible reasons seems to exist. I have no problem with that but people who want to discredit the gospels do.
Mark clearly has Jesus die on Passover day, they even have the time.
"
After the disciples eat the Passover meal they go out to the Garden
of Gethsemane to pray. Judas Iscariot brings the troops and performs
his act of betrayal. Jesus is taken to stand trial before the Jewish au¬
thorities. He spends the night in jail, and the next morning he is put
on trial before the Roman governor, Pontius Pilate, who finds him
guilty and condemns him to death by crucifixion. We are told that
he is crucified that same day, at nine o’clock in the morning (Mark
15:25). Jesus, then, dies on the day of Passover, the morning after the
Passover meal was eaten.
"
In John it's on the day of preparation and even gives the time:
"
After the meal they go out. Jesus is betrayed by Judas, appears
before the Jewish authorities, spends the night in jail, and is put on
trial before Pontius Pilate, who finds him guilty and condemns him
to be crucified. And we are told exactly when Pilate pronounces the
sentence: “It was the Day of Preparation for the Passover; and it was
about noon” (John 19:14). "
Again, John is the first to call Jesus the lamb of God so it makes perfect sense John changed it for a theological purpose.
Demonstrating these stories are being made up.
The writers are very clear here and to do the changes like you suggested above you have to say one Gospel was mistaken, which means they have an inconsistency.
"Noon? On the Day of Preparation for the Passover? The day the
lambs were slaughtered? How can that be? In Mark’s Gospel, Jesus
lived through that day, had his disciples prepare the Passover meal,
and ate it with them before being arrested, taken to jail for the
night, tried the next morning, and executed at nine o’clock a.m. on
the Passover day. But not in John. In John, Jesus dies a day earlier, on
the Day of Preparation for the Passover, sometime after noon.
I can’t give a full analysis here, but I will point out a significant
feature of John’s Gospel—the last of our Gospels to be written,
probably some twenty-five years or so after Mark’s. John is the only
Gospel that indicates that Jesus is “the lamb of God who takes away
the sins of the world.” This is declared by John the Baptist at the
very beginning of the narrative (John 1:29) and again six verses
later (John 1:35). Why, then, did John—our latest Gospel—change
the day and time when Jesus died? It may be because in John’s
Gospel, Jesus is the Passover Lamb, whose sacrifice brings salvation
from sins. Exactly like the Passover Lamb, Jesus has to die on the
day (the Day of Preparation) and the time (sometime after noon),
when the Passover lambs were being slaughtered in the Temple. "
In other words, John has changed a historical datum in order to
make a theological point: Jesus is the sacrificial lamb. And to convey
this theological point, John has had to create a discrepancy between
his account and the others.”