Well, for one, Hermione and Draco's relationship would be completely different. They would have to accept that they are family. Draco might start to respect Hermione more because of their shared blood. Harry would also have a different bond with Draco. They would probably have to protect each other, and this newfound brotherhood could make Draco question his loyalty to the pure - blood ideals of his family. And Hermione would be there to support both of them in their journey of self - discovery.
In this fanfiction, the relationships would be turned upside down. Harry and Hermione's friendship would be even deeper as they are now triplets. They would have an even stronger bond of family on top of their friendship. Draco would be forced to fit into this new dynamic. His relationship with his Slytherin friends might change as he is now related to a Gryffindor and a Muggle - born. The whole Hogwarts community would be shocked by this new relationship between the three, and they would have to deal with the stares and whispers while also figuring out how to be a family.
The relationship between Harry and Draco would change drastically. Instead of being rivals, they would have to come to terms with being brothers. There would be a lot of initial tension as Draco's Slytherin upbringing clashes with Harry's Gryffindor values, but eventually they might learn from each other. Hermione, being part of the triplets, would act as a mediator between them.