I've recently picked up again my research on Rev William Groves (father of Marjorie Montgomery Groves) after a gap of several years as
a) his second wife (Barbara Brown née Bishop) was my great-aunt (my mother's aunt)
b) William Groves had his last appointment apprix 1935-1936 in Settle (where I live, which is just one of those coincidences, but there is a connection with my father's family 20 years before my mother and my father had even met)
In the interveniing years, lots more information, records and material has appeared online. For example, I have recently discovered a copy of the The Primitive Methodist Leader January 13 1910.which reports on the 1910 marriage of Rev William Groves to Frances temple/Winton, daughter of Mrs Winton, otherwise known as Sister Frances, who was also a missionary.
https://www.escholar.manchester.ac.uk/api/datastream?publicationPid...
(in the above newspaper, there is first the short anouncement, then later in the same publication, there is a more details report).
It is not yet certain exactly when Barbara married William Groves, but this happened in Nigeria (there are family recollections of Barbara going out to Nigeria to be married).
FWIW, Rev William Groves died in Settle, he was cremated in Edinburgh, and his ashes were sent to Ikot Ekpene at his request.
Further, Barbara died in 1967 in Edinburgh.