This is probably a variation of Salvin and Selwin, which are English surnames which have three different possible origins, according to Reaney &
Wilson's
A Dictionary of English Surnames. First, they can be frome the Latin name
Silvanus, which is based on the Latin word
silva, which meant "woodland"; second, it can be from the Old French word
salvagin, meaning "wild, savage"; or third, from an Old English given name,
Selewine, composed of syllables meaning "hall" and "friend".