If Wikitree doesn't show a connection, its possible that the information in WikiTree for this branch of the family may be incomplete. The database is limited to the information that is entered.
Another idea is to look for a connection rather than a relationship. The relationships are parent to child, etc. The connections shows relationships by marriage, where there won't be DNA passed down. But the woman who married my uncle is still my aunt, and my step-mother is still my step-mother.