How do I edit

You may be able to select the right parents from the relation tab of those children.
If they are not in the parent dropdown list go to tree view and move the children to the correct parents and specify that that those are the parents (that will disconnect them from the wrong parents without splitting the tree)

There are a number of help pages in Geni, you may want to look at those.
Some links can be found on this project https://www.geni.com/projects/Nederlandse-handleiding-GENI-voor-Dummies/13048 (English version, bottom of page)