if you use the GRO index, on the same site that you use to order certificates,
https://www.gro.gov.uk/gro/content/certificates/login.aspyou can check for mother's maiden name in the years before it appears on FreeBmd. Also age at death before it is shown on transcriptions.
I've been looking for the children of David & Jane to see who might be the mother of Julia. There are baptisms in Vaynor to David, quarryman, & Jane Roberts for
Mary 4 July 1833
Robert 24 Feb 1839
Jane 27 July 1841
Elizabeth 18 July 1844 possible burial aged 15 months 16 July 1845
David 22 Dec 1851
Marriage in Vaynor parish church 14 Oct 1854 by certificate (not banns)
John Jones 28 bach quarryman Garn Vaynor father Rees Jones deceased
Ann Roberts 24 spinster Ponsticill father David Roberts quarryman
witnesses David Roberts & Jane Roberts, all marked.
Possible baptism for Anne in Llanwrin, Montgomeryshire 19 Dec 1830 illegitmate daughter of David Roberts, labourer of Merthyr Tydfil, and Jane Jones, servant of Llanwrin.
Marriage in Vaynor 16 Feb 1833 for David Roberts & Jane Jones, witnesses William Jones & Gwenllian Jones, all marked.