haven't found the marriage as yet, but I have found the burial & death reg of Margaret
burial - 6/10/1840 aged 53 in Disserth parish church, death reg Margaret Wall dec qtr 1840 Builth vol 26 pg 207
Edward then remarries
Edward Wall sept qtr 1847 Builth vol 26 pg 349 with Hester Hardwick the only other on the page. As the second marriage is after the start of civil registration, it should give you the name & occupation of Edward's father
1851 Cefnbach, Disseth HO107/2488 folio 128 pg 7
Edward Wall head mar 72 farmer of 30 acres b. Herefordshire, Yarpole
Easter wife 46 b. Radnorshire, Nantmel
Amanda Hardwick step dau 12 b. Radnorshire, Cefnllys
Baptisms in IGI extracted batch C057661 for Disserth to Edward & Margaret Wall
Jane bp 14/1/1821
Thomas bp 31/6/1828 - buried 24/9/1828 aged 4 months
Jane marries june qtr 1841 Builth vol 26 pg 495 to Edward Samuel - the page number he is on looks to have been mistranscribed when handwritten GRO index typed. He's on FreeBmd as pg 405, but that page number is not within the range for Builth for that quarter.
1851 Penbank, Llanelwedd, Radnorshire HO107/2488 folio 229 pg 5
Edward Samuel head mar 36 farmer of 12 acres & ag lab
Jane wife 30
Elizabeth dau 8
Margaret dau 5
Edward son 3
Thomas son 3 months b. Llanelwedd
John Wall visitor 24 ag lab
John Rice Watkins visitor 26 railway clerk b. Llanelwedd
all born Disserth except where noted
1871 Penbank, Llanelwedd RG10/5575 folio 5 pg 4
Edward Samuel head mar 54 farmer of 10 3 4 acres b.Disserth
Jane wife 50 b. Disserth
Edward son 22 farm servant b. Disserth
Thomas son 19 coal & lime clerk b. Llanelwedd
Edward Wall father-in-law widower 93 annuitant b. Yarpole, Herefordshire
Rose Anna Price niece 9 b. Disserth
hope something here is of use.