Hi Edmundo, Are you using PAF 5.2 ??? I have 3 ancestral lines that preferred marrying a cousin 100 to 1 and PAF always shows their ancestry correctly even if they are half-siblings. Match & merge is one way to fix your problem but here's an alternative if you have this problem again: (1) If the "sibling" ancestors are not shown with their correct parents, FIRST write down that siblings RIN (2) then REMOVE that child from its incorrect parents (2a) if the marriage is also incorrect, just DELETE it and the incorrect spouses (3) ADD that child to the correct parent !!!