The whole real dad being the holy king/pope person is an interesting train of thought!
I also think she's the real (half)sister of the three dual children, but I'm also considering whether the count's wife, the fairy (who supposedly was pregnant according to an earlier chapter?), may have traveled to the past in order to safely bear her child and the whole time traveling, not being able to meet her other children and lover and having used up so much power is what made her finally descend into madness?
So for me it's either A) she fled already pregnant from the church, then went crazy and lost her memories and then met the count etc.
or B) fled from the church with her memories already gone, met the count, got pregnant and regained her memories but wanted to protect their daughter (only daughters turn into fairies) so she fled into the past so that the temple doesn't take her fairy child from them qnd experiment on her
Sooo from what i understand ( it’s not a spoiler since it juste assumptions I m making from those chap uploaded)she is their step sister.. he can’t be her father cause because of the chronology soo I really wonder who her reel father is I hope it’ s what I have in mind ( I kinda of think it s the holy master because of the chronology of the ml birth )
The Mother ( the fairy) had the ml their went into madness where she lost her memory that met the count and had with him three children… that s what I understood