You currently have that person's wife twice on your tree. You will need to delete one of them. It is probably easier to delete the wife of the husband than the daughter of her parents. Once you have deleted the wife, you need to attach the daughter of the parents to her husband.
How you do this depends on whether you use the on-line version of MyHeritage or whether you use FamilyTreeBuilder (FTB).
In the on-line version, you can click on the "plus" sign underneath the daughter's record and select "attach to an existing person."
In the FTB version, you need to "Edit details" of the daughter, then select from the pull down menu "spouse," and then "attach to an existing person."