How to calculate multiple taxes on a sales order?

 Hi all,Yes, I'm new to this forum and fairly new to the EBTax module.  Apologies in advance for any misunderstandings I have on how EBTax works.  I have done some research and testing on this but still haven't figured it out.

We use Vertex Q-Series to calculate our tax on sales orders.  I am trying to see if there is a way to add another sales tax on top of the Vertex tax calculation.  From what I have read in EBTax user guide, standard tax classification codes are the only option available in OM to determine tax.  So, the problem I am having is trying to find a way to combine both the vertex calculation with another tax while using the same STCC.  From what I have seen each STCC must be tied to a specific tax.