Firstly, there are no children in your model at all. Its just one single mesh with no children.
Secondly, Milkshape files dont load up with children to my knowledge. They load up as separate meshes and that is when you correctly allocate bones and materials into the model within milkshape etc...
What you can then do is play an animation on the model and get various parts moving relative to others. The meshes are the children.
Anyway, back on topic. If you want to mount the camera on one of the spheres then you can simply move the camera to the kite objects location and rotate it to be the same rotation as the object then move the camera back along its local z axis. This way the camera always follows the object at a set distance behind.
If you REALLY want to follow the sphere or use it as your camera mount position, then allocate a bone to it in Milkshape then offset the camera with the bones location. Use theGetObjectBoneWorldX,Y,Z() and these give where the bone is in the world and you can also get the bones angle with GetObjectBoneWorldAngleX,Y,Z
So basically I took your model, added bones and added animation of the rear sphere to move it about a bit like a fish flapping its tail. The rear sphere is attached to bone no6.
I then did a real quick program to show the animation playing and the bones location in 3d space (printing out its location.
You would simply use those coordinates as the camera position to animate the camera postion by playing an animation.
