I went a little nuts with this family combining RD and Scoot's family, only instead of Rainbow being her aunt like i've seen they're cousins.
so this goes all the way to our girlies grandparents
Thistle Whistle was once an Equestria wide famous race mare in her youth, competing in all sorts of races. While she doesn't have an undefeated win streak, she was still able to keep herself relatively steady, with her favorite races being challenged based or obstacle flying. She met her husband however before all this fame, the two being school sweet hearts that worked out. once Thistle's racing career took off Splash took up role as her manger helping her out with the sides of things she had issues with. The two had three mares together. With each having their own unique quirks.
The eldest Windy Whistle, didn't catch the racing bug however she did get her dad's knack for management, at first getting an office position in the weather factory she quickly worked her way up the corporate ladder. Where she met the luckiest stallion around, her husband Lucky Bow, who was but an humble blue collar factory worker when the two met. The two had a beautiful foal together whom did get the spirit of a race horse from his grandmother.
Thistle and Splash's middle child, Firefly, was much more soft spoken, not wanting this spot light she had on her because of who her mother was. So whenever the family went somewhere new she ran off on her own, enjoying the sights of nature. Her favorite being the insects of the world, as she got older she went to college for etymology and moved out of Clydsdale. Instead living in a quiet more rural small town of Ponyville where she can be left at peace. Meeting her wife in this town, being neighbors at first Holiday Shine was the kindest mare to her. Helping her move and with anything she need in the spirit of being a good neighbor. It was 4 years before the two moved in together and another 2 until they were officially married. Both enjoying this nice slow pace. Now the two have more responsibility however with caring for her niece Scootaloo.
The youngest mare Mane Event fell in love with all the travels. Whenever her older sister went off during the families travels Event was never far behind, where Firefly found joy in the quiet Event found joy in the loud. Seeing these untamed sights of nature as this whole entire adventure containing artifacts and treasures waiting to be discovered. As she was attending school for archeology, she bumped into this stallion with his nose buried into a camera. Snap Shutter and Mane Event hit it off immediately with both being dreamers and big thinkers. They both dropped out of school and ran off to start their own treasure hunting careers. Mane Event finds these rare and unearth items and places and Snap Shutter both records their adventures and takes pictures, at first they'd sell their findings to museums with that being how they made their income. However soon their little two pony show would catch off life wildfire, with millions waiting for the next episode with baited breath. The two have a daughter together named Scootaloo, she is a very young school age filly. Not old enough to travel around so the two left her in the care of her aunt, in fact Scootaloo was dropped off the moment Mane Event was healthy enough to go back to work. Firefly and Holiday are current in a long and drawn out annoying legal battle to gain custody of Scootaloo and take it away from Snap and Event
Rainbow Dash is the child of Windy Whistle and Lucky Bow, she has the largest spirit of the entire family. With more energy than any pony knows how to deal with, a lust for racing, and an egotistical streak that only gets enhanced every time he wins. Rainbow is a serious hoof full, he used to live with her parents in cloudsdale joining every race possible and doing what she can to live like her grandmare. The pony he looks up to the most above all. When the mobile city flew over Ponyville for the summer solstice celebration, Rainbow ended up making 5 new friends. Friends he helped save the queen, and bring back the forgotten princess with. She decided to move to ponyville to stay with her friends instead of leaving as soon as the city went it's way. Her parents helped her get an apartment however it's up to him to keep up with rent. So now the grandchild of a legendary racer is stuck in a dead end retail job in order to pay rent, however he hasn't given up her dreams of being as famous and good a racer as Granny Thistle.
Scootaloo is the youngest of the family, the daughter of Mane Event and Snap Shutter she is still only a school age filly. Her parents are never around sadly yet she grows ignorant of their failings seeing her mom and dad ass the second coolest ponies around. With the number one spot being her older cousin Rainbow Dash whom she looks up to. However being the fastest Pegasus isn't exactly easy, given her disability. Scootaloo was born with underdeveloped wings, that will never grow to a proper size to fly. She won't let that stop her however, instead using her wings to generate enough wind to let her reach intense speeds on her scooter. On top of this she knows many tricks that impresses her two friends to no end. She currently is being taken care of by her two aunts Aunt Firefly and Aunt Holiday, yet it isn't uncommon for her to spend nights with Rainbow Dash. (by her own request)