loading Wav files into Synth V

I am using Synth V as a plug in within Cakewalk. I want to load a Wav file (of human vocal track), I can only do this when using Synth V as a standalone and I have to drop it into the track. When I then open this file as the cakewalk VST, the wav file is there, but when I save inside the host, and come back the next day the wav file is a blank track, the only way I can use this; is by saving outside the host and then reloading it when I have the next session. Does anyone know how to load inside the host as a plug in and how to make sure that when I save inside host that the wav file is preserved for the next session?