[Tibor]

Thanks for the quick reply Steven! I see your point. You might want to have a look at the way the UI is done in Posts2Posts; very much the way it works with tags, which is very convenient.

I have now solved it using the ID in a custom field (works perfect actually), but am still tempted writing up a custom post type for the trainers, since it does make a lot of things much easier, API wise.

Thanks anyway (I do still think your plugin is a great BTW).