I haven't created a family tree, though I know others on this site have. If your looking for a comprehesive family tree that includes all Forshaws I doubt such a thing is exists or is possible.
If you are looking for a good starting point to compile your own, I would check out http://www.familysearch.org/http://www.familysearch.org/. This is a site hosted by the Latter Day Saints. They are conducting a project that that includes tracing everyone's genealogy and they have compiled an unbelievable amunt of genealogical information. It's free and they won't try and get you to join their religion or anything.
I am more interested in the "broad strokes' version of the Forshaw History - which would be closely tied to the history of where we lived.
I have been looking for information that would substantiate a Danish or French connection - Faurschou or Fougere respectively.