Different Columns for different projects

Hi, 

I have two projects, say A and B.

A has sub-projects say A1, A2, A3 and B directly has tasks. 

Project B needs reduced set of columns and few custom fields. I've created custom fields from Settings->Configure->Work Plan. 

I clicked on B & setup columns required by B. 

However, when I click on A, I see that the columns I had setup for B, also appears for A. When I click on A1/A2/A3 B's columns appear at sub-project level too. 

If I alter columns for A, or A1/A2/A3, it appears in B too. 

Is there a way, I can have project specific column set ? 

Regards,

Nishant