Here's what I have on G.H Southwick line: G.H.Southwick married Jane Bowron in Peru, NY in 1809. I have skeleton info on his line. His father was George Southwick, whose father was Jonathan Southwick, whose father was Daniel Southwick, whose father was Daniel Southwick whose father was Lawrence Southwick b. abt 1594, England, m. Jan 25, 1622/23, d. Apr 1660, Shelter Island, Long Island, NY. Cassandra Burnell was his wife b. 1594, d. 1660, Shelter Island.
As you can see I've just started on this line, but have been able to trace G.H Southwick back to one of the "main" Southwicks, Lawrence.