It sounds like you will need to build your own custom forum for this use case. The OOTB forum app does not currently have the functionality you are requesting.
If you want to read through the API’s they are here: https://www.wix.com/velo/reference/wix-forum-v2
https://www.wix.com/velo/reference/wix-forum-backend
And to connect you AWS db, here’s an article that can get you started if you need it: https://support.wix.com/en/article/velo-integrate-your-aws-rds-database-with-your-wix-site