Hi, Skarpi - It's probably better if you keep all information about one song in a single thread, and post more messages to the thread if you want to add more information. It's also a good idea to give the thread a title that people will identify with the song you're looking for. If you post a mumber of threads, all related to the same thing, it's hard for people to understand what's going on.
If your thread disappears, just set the filter to 365 days and find it again. Post a new message on the thread, and it will go to the top of the forum menu. It's much better to post a new message than to start a new thread. Start new threads only when you want to talk about something that hasn't been discussed before. I hope that helps.
-Joe Offer-