You have two of the surnames I'm researching in the same area of England. My husband's great grandmother was Alice Louise USHERWOOD. Alice was the daughter of Thomas William USHERWOOD and Sarah SMITH and, as far as I know, the granddaughter of Barnes USHERWOOD and Flora SNELLING. I wonder if they're connected to your SNELLING line?
Thomas & Sarah (SMITH) USHERWOOD went to New York in the early 1880s.
Please contact me if you have any info.