Dep. Requirment should not plan @ WBS BOM and should Plan WBS element level

Hi,

I have a scenario like this.

BOM is A - Finished material

B - Semi Finished

C- Raw material

Now I'm going to attach this A header material to Top WBS element.

I/m attaching B (sub assembly) semifinished material to some other WBS element.

My requirement is when I run the MRP for Top WBS it should only plan for header i.e.) A. Dependent should be OFF.

If I run the MRP for sub assembly B, it should plan for dependent requiremnt ie: for C

Where we can control this depen. off .

Is it possible to maintain the two cases in one project.

Please guide me.

Regards

Chandru