A request I had made by the artist. backstory is a mixture of what I suggested and what the artist edited about it.
 
Anyway, source description:
 
Requested Pairing: Sapphire Shores X Beauty Brass  
An interesting pairing, and a quite cute one! I might make a full family portrait for them. I’m going to use and on a little the requester’s story for them.
 
Beauty had been doing music for lounges and clubs around Canterlot, and Sapphire was scouting along all these different clubs, to try and find a good classical musician she could work with for her latest song. She would later book into a motel that Beauty was living in, but due to an error in the computer, she ended up living in the same room as Beauty for her stay. Beauty was a big fan of Sapphires work, and Sapphire had found her to be quite a good musician and quickly asked her to work on the new song. The song became a success and the pair fell for each other rather quickly. It caused a bit of a scandal when they came out during a show, but Sapphire was quick to defend their love and tell the press to back off. After about a year they had a grand wedding, fitting Sapphire’s style, and then started talking about foals. They turned to science and settled on a test tube baby. Two Step grew up watching her mothers from the sidelines, and during every rehearsal, taking a liking more to the dance aspects of their profession than the singing or music playing.
 
Two Step:  
Personality: A sweet and dedicated teacher, she has moments where she can appear to be very snobby and critical. If it’s not perfect, she’ll make you do it until it is.  
Occupation: Dance instructor for many of the biggest preformers in Equestira.  
Cutie Mark: A series of dance steps
 
MLP Belongs to Hasbro