I see similar add-ons, but not what I'm looking for exactly. I need to split the existing permission "Post Replies" into two "sub-permissions":
Can post replies to own thread
Can post replies to other's threads
The purpose behind this: We require a premium upgrade to post NEW THREADS (ads) in our classifieds forum. ANY member can post replies. However, after a user's premium upgrade expires, they should no longer be able to post in their own threads (they shouldn't be able to bump their own ads). However they SHOULD still be able to post replies to OTHER's threads as a regular member.
I believe the above permissions should be able to accomplish this... Let me know if you're interested!
Yes, just note that after you install, you must set your primary usergroup permission (registered etc) to ALLOW "Post replies to own threads" and "Post replies to other's threads" (along with the old "Post replies", which should already be set to allow). Otherwise by default nobody on a live board will be able to post anywhere.