@Psicho Fangirl yes it would be the 1st prince, 2nd prince, 3rd prince, and 4th princess. It's meant to be the order of birth not specific or separated into groups by gender.
See my lists
ROMANCE:
https://mangabuddy.com/manga-list/171140
BL:
https://mangabuddy.com/manga-list/171146
ACTION:
https://mangabuddy.com/manga-list/171150
https://mangabuddy.com/manga-list/171146
ACTION:
https://mangabuddy.com/manga-list/171150