Davis / Chaffe

[furn]

I am trying to find info on a Martha Ann Davies who married a William Henry Chaffe  Driver A.S.C.14101 ( Coal Hewer) & they had 2 children.
William Alfred George b.7/7/1918 (died 27/5/1940 war)@ 21 North Terrace Mardy U.D. and Megan Chaffe b.5/4/1924. died 1942
At the time of William Alfred George birth they were living at 17 Pentre Rd, Mardy. Rhondda.
William Henry remarried an Elizabeth Ann Phillips 1926? and they had a daughter October 1930, presumably Martha died after Megans birth 1924 & prior to 1930.
I cant find any marriage for William & Martha .
Would anyone know where to look for Marthas death details? It has been suggested she may have been buried Ferndale Penrhys cemeteries?
Any help appreciated