What in the world are you talking about ? Belzebu talking thru your daughter ? Ever heard about people talking during sleep saying non-sense, or even
anwsering questions and when wake up cant even remember they were having a conversation ? I do that all the time lol
Im not saying its impossible, but hey, every story has two sides; seems like you are only seeing the evil one

There is a lot of stuff you can read
about sleep, you will see people do the most outsatnding/crazy stuff while sleeping, and its all natural. Anyways, even assuming some spirit was
talking thru your daughter why would be Belzebu ? Why not other one ?