Shipping Address | Billing Address (< add this..) | Vendor Address

Since there is important business logic and conditionals in that QWeb report_purchaseorder_document XML for Shipping Address and Vendor Address, you obviously don't want to create a brand new 3-column in Studio and blow all that existing XML logic away. You simply want to insert a 3rd block below for "Billing Address" as a middle div column to that parent address row div:

<t t-set=[something here other than information_block?...] t-if="res_company">
    <strong>Bill To:</strong>
    <div t-esc="res_company.name"/>
    <div t-esc="res_company.street"/>
    <span t-esc="res_company.city"/>
    <span t-esc="res_company.state_id.code"/>
    <span t-esc="res_company.zip"/>
    <div t-esc="res_company.state_id.country_id.name"/>

</t>

Every attempt I've made so far either remains outside the address row div container or disappears entirely when viewed in the report.

Thanks in advance for your tested solution.