I had my first two ld's the other night. I wanted to see my best friend, and my girlfriend, and i managed to make them both enter my dream. However, when I studied their faces, the details weren't exactly right. Why is this?
That's how dreams are: you see a piece of paper, but the writing is all screwed up. You see a television, but the images are bizarre. You see someone you know, but they look different--and yet you know it's them.
There is probably a way (and perhaps the more experienced lucid dreamers can comment) to master the art of concentration to the point where not only does everyone in your dream look exactly like you want them to, but you can sustain their appearance for a long period of time.
However, since I have only just begun my career as a lucid dreamer, I'm only speculating about this. The input of some of the 'veterans' would be interesting.