Help me look for this manhwa:

I forgot the title and much of the plot but I remember that it was shoujo, transmigration. FMC woke up in the body of a girl who was a made in a countryside inn. I remember that the owner of that inn was an old guy who was a bit perverted. She heard about a noble (duke?? Idr) who was looking for his sister. Said sister has a birthmark on her leg. Turns out FMC transmigrated as the sister. That's about everything I can remember. I think FMC has red hair too. (๑•ㅂ•)و✧