Since the profile is private only a trusted list member or Profile Manager can edit. Since your the profile manager you can edit this by following this example
To change a parent, sibling, spouse, or child relationship, click to the edit page for one of the people.
Then look in the right column under "Edit Family." Under the Father, Mother, Siblings, Spouses, and Children sections you will see links like "" and "[add/remove a spouse]".
See: Editing Family Connections
There is also a Youtube Video See: Editing Relationships