What is a moment where you were glad Delphi had Nyx and Natalie by her side?(When they are sixteen)
Numerous times. A few highlights:
When they were six, and playing on the grounds of the Carrow estate. Two members of the long-defunct Order were attempting to kidnap Delphi - we had kept her relatively out of the public eye, and they could not agree on which child was truly Delphi. The girls all kept changing their names, each claiming to be Delphi. Nyx almost had them fooled - when they reached for her, she bit one, performing some accidental magic as she did so to make the bite become instantly infected. By this time, Severus and Alecto had appeared on the scene. Nyx was lauded as a little hero.
When they were eight, and tried to climb to the roof of my manor, and Delphini slipped. Natalie had the sense to call for an adult even though Nyx and Delphi begged her not to - despite the fact Delphini was hanging off a second floor gutterpipe.
When they were ten, and the three got lost on a broomstick ride through the forest, and they worked together to navigate back to Rosier manor.
When they were twelve, and decided to open the Chamber of Secrets (there was no basilisk in there at the time, so truly it was a harmless adventure - other than the risk of becoming lost, or else discovered by the professors.)
When they were fourteen, and got into a scuffle with some Gryffindors in Hogsmeade.