Thank you for using ROP!
For the moment, it is not available the selection of both “common hashtags for all” and “hashtags from categories”. As a workaround, you can try do something manually, using the custom fields. Here is a doc that might be helpful – https://docs.revive.social/article/480-how-to-use-custom-fields-content-url-hashtags-in-revive-old-post.
I have forwarded your idea as a feature request to our development team for review.
Thank you for being part of our community!