I have two questions - one general and one specific.

#1, what are some good resources I should look at to learn how to work with point clouds? So far, I've only gone through the tutorials in Civil 3D's help file.

#2, I have a large site where the person flying the drone captured points in three separate flights, so I have three point clouds. Cloud 1 is off by itself and clouds 2 & 3 are adjacent to each other. I added all three clouds to one drawing and created two surfaces. I was able to add cloud 1 to surface 1, but when I tried to add clouds 2 & 3 to surface 2, nothing happened. I'm not sure where to start trouble-shooting and I'm not sure that what I'm trying to do is really the best thing.