VideoBuddy

How do I fade in sound/video over multiple clips? I have three short clips, each of about 2 seconds, of a crowd that I would like to fade in both the sound and video over a period of about 5 seconds. When I try this, only the first 2 second clip begins to fade in, but the rest are not part of the 5 second fade in. I have grouped the clips thinking this would get me the 5 second fade. There must be a really simple way of ping this fade over multiple clips but for the life of me I can’t figure it out.