Mariah J Watts GZHG-RJY is not married to her brother Charles Henry Watts KHY1-MDBT
Their parents are Milton E Watts GZHG-K3N and Paracinda Caroline Porterfield 27S5-578
Here is a link to an article that should help you with that: A person in Family Tree has the wrong spouse.
Mariah J Watts GZHG-RJY and Charles Henry Watts KHY1-MDBT are shown with children. Whose children are they? I would first go to the profiles of each child and remove the parental pairs that don't belong. Click on the edit pencil beside the child's name listed under the wrong parents, and in the pop-up menu delete the child link to the parents.
Screenshot for Beulah Watts:
Good advise from dontknowyou after you have removed the children from the wrong parent, you can the remove the incorrect spouse