What if Pear Butter had gone with Grand Pear and the rest of the Pear Clan instead of impulsively marrying Bright Macintosh? Applejack, Apllebloom, and Big Macintosh’s mother was still named Buttercup, but she was a different Mare from after Bright MAC got over the Heartbreak of losing Pear Butter. It would have been Pear Butter who came back to Ponyville instead of Grand Pear in order to try to make peace with Granny Smith for breaking her Son’s heart.
I doubt the three would be born, I think they would be completely different ponies