Ahh, okay. I think I understand. With the default settings, this specific use case should already be possible.
With the following settings at default, collections can be organized in a few ways depending on how your community prefers to structure RPs.
collection_by_topic_owner=true
collection_by_topic_owner_allow_groups=tl1
collection_modification_by_allowed_groups=admin,moderators,tl4
Setup 1: GM creates main topics, Players create individual CS.
The Gamemaster (GM) creates topics for the RP (Main, Lore, OOC).
The players creates individual character sheets (CS).
The GM creates a collection with Main, Lore, OOC. Then creates a section header for CS.
Players create separate topics for their characters. Players can create subcollection of links on their own topic.
The GM adds players as maintainers to their collection. Players add their CS topics under the section header.
Players can still use their subcollection, which only they have permissions in, while the RP group as a whole can navigate to and from the character sheet. The only downside is that the subcollection is public, so may degrade the main experience for other users if they navigate to a players character sheet.
Setup 2: GM creates main topics and single topic for CS. Players reply to topic with characters, and have a private notes topic.
The GM creates topics for the RP, including Main, Lore, OOC, and CS.
Players reply to the CS topic with their own characters.
The GM creates a collection of all the main topics. In the CS topic, the GM creates a subcollection, with links to each individual character post. (Alternatively, the GM creates the subcollection and adds all players as maintainers to add their own links)
Players maintain their own private topic of notes and drafts. Players can create a subcollection on this private topic and link to the RP topics.
With this, the RP is organized by what the GM wants to display. Players are able to access the RP from their own notes without disturbing what the GM has setup. The downside is that players can’t navigate from the RP back to their notes easily (but that can be solved with bookmarks). And players have to use their own topic for subcollections, which may not gel well for those who don’t create/maintain personal notes for their characters.
This is actually setup the forum I am a part of uses and this plugin is designed to fit.
I think the main issue here is that collections and subcollections are always public. So in example setups, while the subcollection can’t be modified by others, they are still visible. Similarly, this plugin is designed for topic owners to have more control on what gets displayed, hence the permission system and various restrictions on linking. These issues can solved by with a hypothetical feature of personal collections that do not impact the public view of topics. This would also more neatly cover other scenarios you mentioned. I’ll think more about creating that feature, and how to make it fit alongside public collections.