To make a long story short, if a mod changes GREETINGS, and also uses the AddTopics box to add topics when the new GREETING is played, this functionality will work fine unless another mod which also changes GREETINGS is loaded after that mod (whether or not the second mod also AddsTopics). The deal is that the engine is supposed to increment the AddedTopics IDs when another mod then later changes GREETINGS and doesn't (or doesn't do so correctly, or something along those lines)-- in any case the result is that the topics are still there, but the "connection" between the name of the topic and the ID the game thinks that topic has is lost, so the game can't find the topic to load, so it doesn't (of course). But this will only happen if another mod which changes GREETINGS loads after the mod using the AddTopics box; what's worse is that both GREETINGS themselves play normally, so the mod seems to be working fine.... except that you can't get the quest or whatever, because the topic itself does not appear.