Hi Pete,

If you use the Onyak Portal Sign Up module, this effectively happens by default for the admin 'owner' account. Please note the accounts aren't synchd though, so a password change on one portal wouldn't populate through to others.

I've had good results with the DNNMasters Multi Portal User Sharing module to get round this though. There are a couple of things to be aware of with this however, firstly delete a user from one portal, they're gone from all, and secondly a user carries their permissions with them across portals, so you have to use admin level accounts very sparingly - it's a good exercise in learning to set up and use roles effectively!

Hope that's of some use.
WK