My grandfather's name was also Arlie Forbus; however, there was a big disagreement in the family about how to spell the name so in some cases individuals were inconsistent about it for themselves and their children as well as for branches of the family.My grandfather was b NJ, lived in Ohio and d IN. As far back as I've gone, I've found it spelled both ways.
Don't overlook the Forbus as a Holland connection.Some Scots Forbes went to Holland for religious freedom but realized that their children were growing up more Dutch than Scottish, so they came here--especially to NY and NJ.A hint for this would be if any of their given names would end in "us".
Most Forbes were Northern Irish Presbyterians--some who came over early on were Catholics who left or were deported from Scotland for religious reasons. Look for names such as Calvin or Marcellus or Wesley as given names--these indicate religious leanings (an understatement, in my family's case).Look for Methodist, Dutch Reform, and Presbyterian connections.