[quote=@Ellri]
It might be far easier to have a separate field from the post field that is titled something like "Characters involved". Initially, that could merely be a text field, but later it might be linked up to more complex features.

A theoretical bonus from such might be for both/all post authors to be credited for collab posts.
[/quote]

The only problem I see with that is that it feels virtually synonymous with the character tab. From my view, the ability to switch between characters would be incredibly advantageous for many RPs.