I've been trying to figure out how I can take a series of spheres and "attach" them to a spline whose vertices are animated. I've tried to simply parent the sphere to a line, but when I animated the vertices of the line, the spheres don't move. I know I can use animation constraints to control the sphere's transforms, but it animates along the path. How can I ensure the sphere stays put on the path while conforming to the shape of the line?
This sounds like an IK-case. But not the usual one. There is a special IK in max, called spline-IK. Check the max-reference under this keyword. This might give you a start. Don't worry, it's pretty easy.