@Zexalfan I haven't read the manga but the LN dished out a bunch of details and blatant hints during their character introductions and in the side stories.
Sophia/Acchan is probably the weirdest among the 7 main members of Bakarina's harem. She has loved Katarina (romantically) ever since their previous life. And as much as she would love to be the one to end up with Katarina, she would rather have Katarina marry her brother.
Part of the reason is probably because Sophia was also hinted to be in love with her brother (actually, Acchan spoiled it very blatantly). If Bakarina never "reunited" with Sophia, the Ascart siblings would definitely be more than just sibling-cons.
@minagi mikoto aren't you supposed to be Mai's though? XD