This is my first suggestion, so my apologies if anything seems unclear! I'll try to keep this short and sweet.

So basically, I'd love an option to pin one or more replies to your thread. What I have in mind is something similar to the option to pin a comment on YouTube, the only difference would be that you can pin multiple messages in whatever order you please.

Why would anyone want/need that you ask? Well, I would personally really welcome such a feature, since it would help me to keep up with my auction thread for example. You could pin the message with the current highest bid, some additional information or updates instead of having to edit the thread.

Another thing I'd use it for, is pinning post I forgot to add in the first place. I'll give you a concrete example for that one. This thread of mine was supposed to be immediately followed by two more replies, containing the "Flatsales" and the "Claimed Cubs" sections. That would have made editing, formatting and managing the thread easier for me. However I sadly forgot to do that and another person had already replied to the thread before I got he chance to reply to it myself. I had to resort to the second best option and moved the two sections to the reply I gave the person who replied first. If I had the option to pin replies, no matter what page they're on, I could simply reply to the thread with the two missing sections and pin them to the main post. Then the main post would be immediately followed by the two other pinned sections and the auctions can just carry on like they normally would! Plus I'd be able to manage everything waaaayyyy more easily.

I think there should be a limit to how many replies you can pin though! The pinned messages shouldn't cover more than the first page.

Feel free to let me know what you think and don't be afraid to ask if something isn't quite clear to you! I'm always open to suggestions <3