Kelly-McCarthy Wedding

This is a photo of the wedding between John Charles Kelly and Mary Ann McCarthy. With them is Ann Kelly (it says no relation) and John McCarthy (brother).It was taken either in Abington, Ma or Chicago, Il. They were apparently related to the O'Connolls and O'Connors of the above two places.

Who were John Charles Kelly and Mary Ann McCarthy? Where did they live? How were they related to Susan O'Connell O'Connor or Austin O'Connor?
People in photo include: John C McCarthy and Ann Kelly