How to find positions and rotations intervals for spawn

I’m trying to find intervals of positions and rotations to spawn the cup in front of the hand so that it is graspable (The cup is child of the hand).
The problem is that I’m moving the mug in the editor in order to find good rotations and coordinates, but sometimes if I move the object along a direction, the other coordinates (or angles if I rotate) also change. Is there an easier way to find ranges of points and rotations in this case?

Scene: Imgur: The magic of the Internet

Thanks in advance

You have two types of directions you are facing: local and global. There is switch in editor of that (you will see difference in arrow direction with moving tool).

More simple solution is just create empty game object in hierarchy of hand. Name it as Spawner and when you instantiate cup put in the method position and rotation of spawner. He will be always on the right place.

Sounds reasonable, thanks!