Hello there,
1. There will be new content for Starcon.
2. Anna is unlikely to share scenes with Norah as they are in separated circles of the stories.
3. Unlikely for Charlotte will have some extra.
4. Samantha won't have a Starmaker profile, she appears at the convention because she is going with Ken.
5. Amelia is unlikely to be fully shared, not impossible, but unlikely.
6. Sofia might receive some content for her romance route, as the slut route has most her content and just got access to the farm.