Change family link

We have learned that the 'parents' of my wife's grandfather were actually his grandparents.  His birth mother was his 'older sister'.  His grandparents raised him and he always spoke of them as his parents.  We don't know if he even knew they were actually his grandparents.  I am debating between leaving him where he is in the genealogy (with an appropriate notation) or moving him under his 'sister' with a notation that he was raised by his grandparents.  Recommendations?