Some families are a little bit complicated. And if one is not careful it can be easy to enter the incorrect relationships in our genealogical database. What I do in these situations is to map out the relationships on paper first in an attempt to get a broader view of the family and in an attempt to understand the relationships correctly.
Once I think I have the relationships down, I begin my data entry. Wasting time "fixing" relationship mistakes is time I could spend doing actual research.