« Reply #11 on: Monday 10 February 20 20:42 GMT (UK) »
the census is just a snapshot, she may have been living with the Evans family since she was a small baby. The family was in Pentyrch in 1861 so they could have taken her in before their move to Llantrisant. It's possible that she was a nurse child and they were paid to look after her, at least at first.
You have her baptism, what is going to give you more detail of her parents? The name of her father probably isn't on her birth certificate. Father's name might not be on her marriage cert. You're lucky to have a father's name on the baptism.
Possible for Jane Rees in 1861 census
Maseason, Peterstone super Ely RG9/4042 folio 10 pg 2
John Rees head mar 56 farmer of 150 acres
Mary wife 54 b. Pendoylan
Evan son 31
William son 28
Ebenezer son 26
Jane dau 24
Edmund son 18
Catherine dau 13
all born Peterstone except Mary
Cornwall: Allen, Bevan, Bosisto, Carnpezzack, Donithorn, Huddy, James, Retallack, Russell, Vincent, Yeoman
Cards: Thomas (Llanbadarn Fawr)
Glam: Bowler, Cram, Galloway, James, Thomas, Watkins
Lincs: Coupland, Cram
Mon: Cram, Gwyn, John, Philpot, Smart, Watkins
Pembs: Edwards (St. Dogmael's)
Yorks: Airey, Bowler, Elliott, Hare, Hewitt, Kellett, Kemp, Stephenson, Tebb