Since I believe I am the person who posted the "No hijacking" guideline suggestion, I'll chime in on what I was thinking. Both of the examples above might warrant at least one new thread, not only to allow both the OP and the new poster(s) to get better answers without having to wade through replies that don't relate to the topic or question of interest to them, but also to be sure that people who are interested in the new discussion topic(s) but who aren't interested in the old one realize that the new discussion is happening. Pointer posts linking both ways in the old thread and the new one are a great way to handle the transition. The intent is not to stifle the flow of conversation, but to stimulate it in a way that makes it more useful to everyone on the forum.