Egmont's grand parents (bottom left corner) had 4 children, 2 of them were severely disabled and died at a young age.
Egmont's father (King Tornese, the one standing in the left side) has three wives, 11 legitimate children (2 disabled, Zosma and Melitta) and at least a dozen illegitimate (these latter are not shown in the picture).
Melitta died 4 days after birth, Zosma is epileptic (as Stilfser) and very weak (he can barely walk).
(For Zosma, I was inspired by the sad story of Charles II of Habsburg, prince of Spain)
PS. Of course all the male kids born in the House of Ytalia are called "Egmont" followed by their respective number, but when I speak of "Egmont" alone I mean Nearco Zavijava (i.e. Egmont CCV, the ruling sovereign for the most part of the story). Just to add more confusion to an already confused story.