Responses
In this, the mc regressed and became the daughter of the family. She will also be friends with the real daughter according to the spoilers so
https://www.mangago.zone/read-manga/i_became_the_contract_daughter_of_the_soon_to_be_ruined_family/
I highly recommend "Beware of the villainess" the MC became besties with the og FL (ノ≧∇≦)ノ
Asking out of curiosity, but are there any romance isekai where the mc becomes friends/good friends with the original mc?