A bit more on this family now, found on Ancestry.
John's brother Hosea Westmoreland completed a WW2 draft registration card in 1942 and named his contact as Mrs Arvesta Wilbon, no relationship was shown.
There is an entry in the Social Security Claims index for Arvester Wilbon, born 19 March 1894, Clindon, Arkansas, (should maybe be Clinton), father Irving Westmoreland, mother Etter Bounds. Arvester died in St Louis, Missouri in 1982.