If you go into the Edit tab for your grandfather you can replace/remove the incorrect father (Ekstrom-303). The link is located just below the father's name. You'll be brought to a new screen where you can enter the correct father's information. If you do not have enough information to create the correct father (keeping in mind you can estimate information such as DOB, but you really should have a source), you can scroll down to the bottom of the page and REMOVE the incorrect father.