So, if I understand you correctly, you have five seperate accounts with five different emails? If that is the case, then what you will want to do is set all the Slingboxes up on the main (admin) account. Then you will need to create a guest password for each Slingbox, and just add the one Slingbox you want on each individual account to the Slingbox directory w/ the guest password, within your account profile page, one at a time. Does that make sense?
Here is an article from our support page that should help with your endeavor:
Hope that helps!
The Sling Moderation Team