How to default the supplier site tax classification on the invoice line tax details

Hello Community.  We are setting up VAT for the first time in eBtax and need some help with defaulting the tax classifications on invoice line tax details.  In a test instance, I have assigned a Tax Classification to both the Supplier and Supplier Site third party in eBtax.  Do you setup a tax rule for this?  If so, how do you indicate that the tax classification should default from the supplier site?

I have researched multiple Doc ID's and community discussions on this and still not able to determine how it works.  I would rather not define a default tax rate and then have to change the status manually on the Tax Details.