Just posting this now for Mary Ann Johnston and possible early censuses for her with her family:
1861
www.familysearch.org/ark:/61903/1:1:M7P9-SP71871 I can't find on FS

But see below:
Henry Johnston 65 widower joiner b. Scotland
David Johnston 20 iron miner
Mary A Johnston 17 domestic servant
William Johnston 15 iron miner
Elizabeth Johnston 12
Family living at Moor Row (or Roe?)
Monica
Added: Just thinking... Thomas and Mary Ann, possible first born may have been John Henry and then daughter Henrietta for daughter. Then we possibly have Mary Ann's father showing as Henry BUT these are just guesses without having seen any registrations