How do I group relationships in a view?

I have an event that references different kinds of speakers in multiple nodereference fields: master moderators, moderators, speakers (generic), panelists, and featured speakers. For a speaker list page, I'm toying with the reverse_node_reference module to look at the parent event to reference what event categories are, and show an exposed filter. Oww my brain cells.

This kinda works, but I have to show 5 exposed filters for master moderators, moderators, speakers (generic), panelists, and featured speakers. I Don't want this. I want one filter for all speakers together to narrow down by what kind of events they are participating in.
OR: I just want to group the speaker view by parent event's category with no exposed filter.

Any thoughts on how to stick a fork in it? I thought about playing with nodereferrer but see the same issues happening so far. Or am I wrong?

Thanks much for the advice in advance.

Chris