In order from right to left:
Skyline (Younger daughter of Soarin and Applejack)- takes more after her father. Easy-going and laid back. Followed in Soarin's footsteps and joined the Wonderbolts.
Applebuck (Older son of Soarin and Applejack)- Stubborn and prideful, but extremely loyal. Helps run the farm under his older cousin Apple Blossom.
Apple Blossom (Daughter of Big Macintosh and Fluttershy)- A mare of few words, she has a head for business and plants. Soft spoken but very sure of herself. Runs Sweet Apple Acres after her father retires.
Sweet Stuff and Sugar Cube (Pinkie Pie and Braeburn's twin daughters)- Very similar to Pinkie and Braeburn with their endless supply of energy. Sweet Stuff (the one with the bow) is a technically the older twin and is a bit calmer and more girly than her younger sister Sugar Cube, who hates restrictive clothing of any kind, though both of them act as though they're on a constant sugar high.

These aren't my only ones either, but I just wanted to do the ones related to the apple family for now.