One other thought! Once you have the names of Daniel and Mary Ann from their marriage cert, why don't you post the details and maybe something can be found on them.
Monica
Daniel McWilliams father was Daniel McWilliams snr mother Ann or Annie think her second name is Convery or Canvery
Mary Ann Murray father was James Murray and mother was Margaret Crawford.
Do you think its ok to post here or will I post on a new one?

Mary Ann and Daniel married at St Johns Chapel, Portugal Street, Glasgow, i think the chapel has been demolished. shame