In my AU Sweet Biscuits and Duke Blueblood are siblings~
 

 

 
Sweet Biscuit knocked the door of Blueblood’s office, after that she opened the door. “Didn’t I told to my secretary to not let anyone in?” He sighed. “Well yeah, but he will let family in” She said as she walked into the room. “Well, why are you here” He asked.“Well I jus-” She started but then noticed what he had worked on “The heritage? I thought we talked that out?” She tried to look what he had written, the she noticed a name “Coriander?” She walked back “Yo-You are gonna give it all to him? Caramel Cream was supposed to get your title?” She said. “Well Caramel is your daughter, but Coriander is my son” He said. “Illegitimate one” She noted. “Not for long” He stated.Sweet’s eyes widened “Y-you are actually gonna commit to something” She said “What do you know if he is even y-” She knew to stop her sentence from his face.. “What about Caramel?” She asked “She is you daughter not mine.”  
She sighed “I-I just thought that after our parents not wanting me…My brother would appreciate me”. Blueblood’s eyes widened. “Y-You..”. “Of course I knew! I know that I’m an accident, I know you are the one who was supposed to inherit everything. I just existed for them, I had to look pretty and classy to hold the status of the family, not needed, not wanted” She stepped backwards. “Fine. do however you wan’t” She said and left the room.
 

 

 
Sweet Biscuit’s name was originally Perfect Gem, she changed it when their parents died, it was little bit way to differentiate herself from the family, Even tough she had used Sweet Bisuit before since it fitted better with her cutiemark. Later she married Donut Joe and got a daughter Caramel Cream.
 
Blueblood inherited most of the wealth and the title, he met mare named Cayenne and accidentally got her pregnant. They got a son named Coriander.
 
Caramel and Coriander: fav.me/dc4j5el
 
(Sweet Biscuit and Cayenne are background ponies from Canterlot, just gave em a story)  
Sweet Biscuit: vignette.wikia.nocooki…  
Cayenne: vignette.wikia.nocooki…