Hello Simone
My gtgtgtgrandfather John Burns (often spelt Bournes, Bourne, Barnes) married Pheobe Marshall in 1839. He was a good 20 years older than her and his first wife had died in 1810.
I believe John died in 1858 and I can't find Phoebe on the census for 1861. She is shown on the 1871 census as Phoebe Burns living in Joyford and in 1881 living in the Alms Houses in English Bicknor. On each of the census she states that she was born at Westbury. Phoebe died in 1882 and was buried at English Bicknor.
Another spanner in the works is that Charles was baptised as Burns at English Bicknor on the 14 March 1822 - father John, mother Phoebe.
I'm afraid I have no knowledge of the change from Marshall to Ward.
Regards
Gill