Tax Exemptions at Customer Bill to Site

Hello All,

We have two customers A and B as shown below and we  have a bill to relationship B to A.  B is re-seller of our company, so most of the time we will have items ship to A but billed B.  Some times we will have invoices directly billed to B and those will be taxable. When we are selling to B and shipping to A we want to setup as tax exemption,on the sales order we will have Ship to as "A" and bill to as "B".  So want to setup tax exemption based on Bill to, if i