Casey Family

Looking for information on my Great Grandmother Ellen V Casey b 1878. Her parents are listed on her marriage record as Daniel Casey and Ellen Ford.  All I know is she came to the states as a young girl with her two older brothers who I believe are named William and Daniel.  There is also a John Casey b. 1860 who is related somehow to Ellen.  I first thought he was an older brother but his parents do not match Ellen's.  I found John's birth record as Newmarket so that has led me to this parish hoping Ellen was also born there.