I just took a good look at that picture. I never noticed it when I saw it before, but like you I don't think it would be possible. Also notice how Barry is in front of Stanley and then in back of his grandmother. In any picture I have with my kids or grandkids in the middle of my husband and I, if they are big enough their arms would be around us or our arms around them.
I think that picture was originally just Stanley and his wife.
Wow this one really looks odd!