Facebook is testing a new option to allow users to reply to specific comments for page posts. Threads on page posts will be sorted by an algorithm to boost the most engaging comments toward the top. This will make comments on page posts more like Facebook’s comments plug-in for third-party sites, which have had both threaded comments and a ranking algorithm since March 2011. “If Facebook rolls out these changes more widely, pages may see increased engagement on posts since high-quality comments will be surfaced up top and users will be notified when someone replies to their comment.” The social network says the new format isn’t being tested on users’ personal posts. (Inside Facebook)