When I merge one topic with another, the one that gets merged loses all comments and replies. It would be nice if those still showed up as comments when they're displayed with the new topic.
I should just mention that how I get around this is by using the re-direct feature instead of merge - but I agree, this is a good idea!
If you merge a topic with replies, we keep the topic, replies but move the votes over to the topic you merged it into.
We do keep the replies, but they are only visible if you click through to the original topic from where it is listed as a reply in the topic it was merged into.