What you can do as a workaround is to set up 3 different installations of eqdkp-plus in 3 different folders and organize the signups and access-management via one common forum like we did.
It's even possible within only one database. Therefore you need to follow these steps:
Create 3 folders in your root and name them swtor, wow and rift (just an example)
Copy all eqdkp-plus files to all 3 folders
Start the installation of the first eqdkp-plus in the swtor-folder (
www.yourdomain.com/swtor/install)
Change the following settings:
Change database-prefix to _eqdkpswtor
Change cookie-name to eqdkpswtor
(if you want to use different databases for each installation you don't need to change the prefixes but cookie names still need to be changed.)
Now start with the next installation in the wow-folder and repeate these steps. Remember to use different prefixes and cookie-names now.
If you completed all 3 installations create 3 user-groups in your forum-settings.
We use phpbb3 but it should be similar in all supported forums.
Call the new groups swtor-user, wow-user and rift-user (again examples)
Finally you enter the 3 different group-id's of those new user-groups in the plus-settings -> cms-bridge section of your 3 different eqdkp-installations (group-id of swtor-user in the swtor installation, etc.).
The users now can sign-up via the forum and you are able to decide, if single users should have access to only one portal or to all of them.
To jump between the 3 portal-installations you could add links from one portal to both others (plus-settings -> link section)
As an example you can have a look at our installation:
http://www.dunkler-aufbruch.deBut of course you will have 3 different raidplanners. In my opinion it is more an advantage than a disadvantage because most players are only interested in ONE gane. Our WoW-players only can see the WoW-part and not the swtor-part and only WoW-players have access to the WoW-portal. This is much easier to navigate for them

Best regards
Elec