こせき
family register; census
JLPT N1 Common word Intermediate Japanese L14
Noun
彼女かのじょはまだ夫おっとの戸籍こせきに入はいっていない。
She has not yet had her name entered in her husband's family.
戸籍こせき上じょうの縁えんは切きれても、昔日せきじつの絆きずなはそのままだ。
Our connection may be cut on paper but the bonds of old remain as they were.
これはおそらく戸籍こせき上うえの出生年月日しゅっしょうねんがっぴを調しらべた上うえで修正しゅうせいしたのではないかと思おもいます。
I believe this may be a correction after investigation of his date of birth in the family register.