This is Caramel and his identical twin sister Butter, fouls of Applejack and Flim. Their cutie marks are melted caramel/butter being poured into a pink cup by a spoon.
Applejack and Flim do not live on Sweet Apple Acres. Since Big Mac was the oldest, he inherited it when Granny Smith died. Yes, Applejack and Apple Bloom still lived there, but when Big Mac married Rarity, the two moved out to find their own paths in life, Apple Bloom now being old enough to live on her own since the present timeline is 19 years after season 7. Applejack moved in with her long distance coltfriend Flim in Los Pegasus, and they started a new branch of the Apple business there. Apple Bloom went to college with Sweetie Belle at Canterlot. Every 2 months, Caramel & Butter visit Sweet Apple Acres for a week, helping to buck the trees and spending time with their cousins; Jasper, Empire Apple, & Diamond Core.