Might need more information or picture of your problem to get this right or the way you want. From what I read using the transformation / multiply scheme / 2 dimensional array should work for you. All the tool paths will be generated at the defined offsets for each operation for as many as you define. You wont see the part or the stock only the generated too paths. From my experience what is generated for the part by selecting surfaces will be exactly copied for as many offsets as you define under the multiply scheme / 2 d array. shown below
Attachment 325162
If the stock needs to be defined with a hole or whatever shape you want "casting or other" the ONE way I achieve this is to draw the material shape to be used and import that igs to use as the work piece defined in the model tab. This should allow you to have a work piece that is exactly what the stock / material looks like.
Then extra tool paths milling air is avoided.
This process can also be extended and copied along with part models but I think is more work then required for what your doing in this case
Also if the transformation function is used its a good idea to check the g code generated . Using the subroutine option will not generate correct code in my experience I can only get copy to work correct.