וַאֲחֵיהֶ֗ם לְכֹל֙ מִשְׁפְּח֣וֹת יִשָׂשכָ֔ר גִּבּוֹרֵ֖י חֲיָלִ֑ים שְׁמוֹנִ֤ים וְשִׁבְעָה֙ אֶ֔לֶף הִתְיַחְשָׂ֖ם לַכֹּֽל׃ (פ)
And their brethren among all the families of Issachar, mighty men of valour, reckoned in all by genealogy, were fourscore and seven thousand.
Rashi on I Chronicles
And their brethren of all the families both of the sons of Tola, both of the sons of Uzzi, both all David’s mighty warriors were eighty-seven thousand.
Rashi on I Chronicles
all having genealogical records This means: according to all their genealogical records.