Sink threads

So, we have recently migrated from Vanilla to Xenforo, but we just recently discovered that we are lacking a feature that Vanilla had and that our moderators were using regularly.

The option to "sink" threads, meaning that as new replies are posted in the thread, it does not rise back up in the forum view, but stays in the same spot and is "sunk" until it eventually dissapears. This was a feature that was very useful for us and I was wondering if there perhaps are some add-ons that can do the same?