Have you traced back the mother-in-law, Elizabeth PRICE b Llangammarch?
Probably the following family?
In Builth in all censuses; all children b Builth. Husband is Isaac, b Llangartten - a roadman/labourer.
1871
Isaac 60, Elizabeth 55, Lloyd 14 (Clerk Weighing Machine)
Four households away is the following PRICE household!
William, Son(!), 31, Painter; Martha, Daughter(!), 29, Milliner & Dressmaker; Sarah, Daughter(!), 26, Milliner & Dressmaker - all unmarried and all born Builth.
1861
Isaac 51, Elizabeth 46 (a Tollgate Keeper), Martha 19 (Dressmaker), Henry 13, Thomas 9, Charles 7, Lloyd 4
1851
Isaac 40, Elizabeth 37, John 14 (Errand Boy), William 10, Martha 8, Isaac 7, Sarah 5, Henry 3, Elizabeth 1
1841
Isaac 30, Elizabeth 25, John 5, William 2
In 1881, together in Builth are Martha 36 (Dressmaker & Milliner), brother Lloyd 24 (Writing Clerk Railway) and nephew Henry PRICE 9 all b Builth.
JAP