The four children of Count Baurendouin de Haillenarte are Francel, Stephanivien, Laniaitte, and Chlodebaimt. But there's some contradicting texts regarding the order they were born in.
Stepphanot says that Francel was the 'fourth born of his father's loins,' which clearly pegs him at the youngest. And in MSQ, Laniaitte says that Francel is her younger brother, which supports this. The contradiction, however, comes from Hunter-scholar of Camp Dragonhead's description of Naul:
“The dragons Naul and Svara are best known for their attack on the Steel Vigil, which left the fortress a smoking ruin. Notable casualties include the third son of House Haillenarte...”
Except the third son is the still-living Francel, and the brother that died in the Steel Vigil was the older Chlodebaimt. This contradiction was most likely just the result of an oversight, but that said, a family tree depicting the members of Ishgard's high houses to determine birth order would be extraordinarily useful...