Tax Included set to No on Payment Schedule, but treated as Tax Inclusive in Payables

Summary:

We wish to treat the invoices created in AP form Lease Accounting as tax exclusive. The field in the payment schedule seems to have no bearing in AP. How can we set invoices from Lease Accounting source to be Tax Exclusive by default? Or better yet, to honour the lease payment schedule Tax Included field?

Content (required):

Invoices generated from Lease Accounting are tax exclusive - e.g. $1,000 excl.

NZ GST is 15%, to be applied on top of the amount sent from Lease Accounting.

AP should add 15% to the 1,000 invoice line where the invoice source is Lease Accounting, or, honour the Tax Included field in the lease payment header.