I got this thru some girl descriptions and the events :

Bipina and chocolate cosmos are cousins, moonvine and ipomoea nil are best friends that grew up on a same orphanage, hypericum is a student of dianthus, cherry sage and scarlet salvia are sisters. And also cherry sage says that her sister works for a transport group, dunno if it's the same group as dahlia's acacia group and I dont know who are the other members.

I guess i'll go read more stuff