Use a unique rel attribute on each link.  The lightbox will group rel attributes into a gallery and adds navigation, so make sure each rel is unique and that should go away.

Thanks Matt. Let me try that. 

hmm.. shud not b 2 hard 2 patch-in such features; w/little bit coding & maybe lots inventive ingenuity.

Thanks Speedysnail6, will check that out.

DhrupDeScoop, I understand he created a great plugin, however, I'm don't think that each elgg multisite can interact with each other on his configuration. I will try to check it out

I'm also really interested in a multisite config where each site can interact with another site rather than stand completely on its own. To be more specific: I'm interested in Marcus' plugin as it is right now, except that I would like users of one site to be automatically users of another site as well. That way I could develop different sites for different target audiences (meaning each site has its own plugins), but still allow users to easily switch between the different sites and do stuff on all of them.

I was thinking that this could mean that each site should still have its own database (like in Marcus' multisite plugin), but should connect to another database when an action concerns the User Entity (i.e. logging in/out, changing user settings, etc). This is probably quite difficult though, given the guid confusion you could expect from such a config... Alternatively, perhaps the multisite concept by Marcus is just too much for this, and I should concentrate on simply finding/coding a plugin that makes use of the Site Entity that Elgg already offers. I don't know. Suggestions/comments greatly appreciated.