If the webmaster has 'groupings' turned on, then yes.
Generally anyone who has more than one site on the same signup form has them turned on.
for example:
here is the standard linking code to one of our sites:
http://refer.ccbill.com/cgi-bin/clic....com/mainp.htm
You can change the last part to any page you like, if you feel that will work better for your traffic