In googlemaster tools subdomain1.widget.com, subdomain2.widget.com and widget.com are added seperately, and although there is an option regarding widget.com and www.widget.com I cant see anything else to help link them together. But I assume when Google does its page ranking it would treat links from subdomain1.widget.com to subdomain2.widget.com as internal, i.e not given the same weight as if from another site such as different.com.
In a similar vein assuming my statement above is correct if I also happened to own different.com and that was listed in webmaster tools would that then also treat links between widget1.com and different.com as internal because under control of same person even though may be completely different sites.
And if I owned both but didnt add different.com to wemaster tools what would do Google then