Are these Grahams related?

Hi i was just wondering if anyone could help me figure how if these grahams family’s are related and if they are how, relatives of mine lived in mountcharles in co donegal in 1901 Ellen Stewart who’s maiden name was graham lived with her husband george and children and i think living in the same place was two other graham families a Edward (Ned) graham with his with catherine maiden name o’neill and children and when i searched his marriage record Ellen Graham was down as a witness and this was before she was married to Stewart so it seems likely it’s her only thing is johns father is different to Ellen’s so i don’t think it’s a brother but wondering if it’s possible maybe this Edward (Ned) is a cousin? any help would be appreciated thank you