Re: info on name Sidella please
"Sidella" appears to be a feminization of the Northern English surname "Sidell" (more commonly found in the northern counties of Lancashire and western Yorkshire).
The name comes from the Old English words "sid" (meaning "wide") and "halh" (meaning "a nook" or "recess").
As with all habitation surnames adopted for use as given names, the meaning is a description of the place from which the bearer originated, rather than a description of any physical attributes of the bearer. Which, in your great-grandmother's case, Mark, is probably a very good thing.
-- Nanaea