If I'm understanding the question right he is asking if there is a way to give access to other protected areas after the member has logged into the primary member's area and that is something that Strongbox does very nicely using a bit of handoff code.
Code:
http://SITEURL.com/cgi-bin/sblogin/handoff2.cgi?site=OTHERSITEURL.com&path=/PATHTOOTHERPROTECTEDAREA/index.htm