I am working on a identical requirement, but I found out that it is impossible to assign more than one template to a business partner.
Also How do I assign multiple Templates to a Business Partner. The reason I ask this is once one template is assigned, the option "New From template" on the Account Overview section - Sales Area part, vanishes.
Now the options available are "New" & "Change Template"
Per template type you can assign only one template to a business partner.
CRM_SALES is the only template type for business partners.
Thus you can assign only one template to a business partner.
Although you can assign multiple templates to a business partner via SAP GUI, when using different template types, only templates from template type CRM_SALES are taken into account and resulting in a sales area assignment.
Since the table BUT0TP supports multiple assignments of templates to business partners ...
... I am wondering if someone knows a work-around (via an enhancement) to enable multiple assignment of templates for business partners?