The George and Dora Simmons' you refer to are my great grandparents. I, too, am very interested in knowing the circumstances of their travels to and from the US. I am in contact with descendants of one of their sons (Alfred, younger brother to Charles and Annie who were born in the US), and I hope they might shed some light on this. I'll keep you posted.
Also, it appears that Annie Kate married a Walter Fitch in Chigwell in 1890, and had a son Arthur George Fitch born 1891. I have not found any further offspring from there.
One son, other than Charles, returned to North America (Manitoba, Canada). I'm working on that one, too.