Priscilla and Raven are blood siblings; however, they got separated when young.
Altena and Aerone are not blood related (ok, they are like 5th cousins or something even further than that). However, that is not close enough to mean anything. They were just raised together. At Medieval times, it was perfectly normal for cousins to marry, and these two are really distantly related (at that time, even Shanan/Lakche, Lakche/Johan(if Lex was the dad), Patty/Lester, Rana/Faval, would be perfectly normal).