I am not the father in law of my wife and my son is is not her husband! How can I correct this?
Here are a few articles from the Help Center that might be helpful:
How do I correct parent-child relationships in Family Tree?
How do I see what changes were made about a person in Family Tree?
How do I undo an incorrect change in Family Tree?
Are you, your wife, and your son all alive? Are you all marked properly as alive? If so, the only person than can see any of these and do any editing is you or someone you have expressly allowed to be a Helper for you. Those would be the only options for the someone you mention.
If you are all alive and any of you are marked as deceased, then you need to get that changed by clicking on the Edit icon for death information and changing the person to living. You will get a form asking how you know this that you need to fill out then within a few days the change should be made.
If your wife or son or both are deceased, may I offer my condolences. If that is the case, then anyone can help work on their records. But they would not be able to see you in Family Tree or edit any relationships to you.
If your wife and son are living, then you can correct by delinking both (remember the PIDs ) then link in correct order.