With GenoPro you can easily relink any individual to another family. The first step is to remove the wrong pedigree link. Select the link and press the delete button on your keyboard.
The second step is to recreate the link between the individual his/her new family.
In this example John will be "Link as Child" to the family of John's father and John's mother.
Futher information about about pedigree link http://www.genopro.com/introduction/ (section Adding members)