Isekai, historic, fantasy, time regression, time travel part 1

Just to let you know I think the grand duke is the ml so it can be weird but the most important is that he didn’t get romantically involved with her until she was 18 and she was the one who started

I need to pickup again but basically she’s transmigrated into the villainess while she’s sacrificing some child for her powers or smt like this
She saves one of the children who’s still breathing and start taking care of him

The fl is transmigrated to the villainess og and she meets another transmigrator, they became allies and try together to change the plot