[quote=@Mahz]
<Snipped quote by whizzball1>

I'll consider this sort of feature when there are actual co-GM-/GM-specific powers.

<Snipped quote by Captain Jordan>

Some day™.

The auto-suggestion system was easy to hook up for the co-GM form since you can only add one at a time, so the auto-suggestion UI can just take over the entire input. But the new-convo form is a comma-delimited list of usernames, so it'll involve some thinking + refactoring to implement.
[/quote]

What I've seen other sites use is the auto-complete textbox to find a name, but then the name leaves the textbox and appears in a non-editable list with [X] boxes to remove entries.