The official Fire Emblem Twitter account has published some additional details about how the Fire Emblem: Three Houses Cindered Shadows DLC connects to the main game’s story.

As briefly explained elsewhere, Cindered Shadows is separate from Fire Emblem: Three Houses‘ main story, and does not use the same save data. However, by progressing through Cindered Shadows, players can unlock The Abyss as a new area for exploration, as well as recruit the Ashen Wolves into their Main House and bring them over to “Part 2” of the main story.

また、本編第一部であれば、散策時に「灰狼の学級」の4名とも交流できるようになります。さらに「煤闇の章」の進行状況に応じて、自学級へのスカウトも順次可能に！
自学級に招き入れた生徒は、戦闘や授業に参加するようになるのはもちろん、第二部でも成長した姿を見せてくれます。 #FE風花雪月 pic.twitter.com/VHFfDrzBSp

— 『ファイアーエムブレム』総合 (@FireEmblemJP) January 29, 2020

The Fire Emblem: Three Houses Cindered Shadows DLC releases on February 13th 2020.