This really doesn't make no sense and i can understand why it has had no replies.!!
But I think I know what you mean if your playing a track @ 115 bpm and your other tracks original bpm is 85 the track playing would be the ''Master'' deck and it isn't possible to get the master deck to drop BPM without turning the Sync feature off. You would have to Sync to 85 bpm track @ 115 bpm. to blend them.
But with such a huge gap in beats per minute this mix would more then likely sound like crap..