Good day @lubos
In the Purchase Invoice I suggest to provide a Address field below the Supplier similar to the Billing address field below the Customer in a Sales Invoice.
We have one-time suppliers who provide services on credit and such services need to be recorded in the Purchase Invoices tab rather than the usual practice of using the Receipts and Payments when the payments are immediate.
So for such one-time suppliers we can create a single Supplier to reduce clutter and enter the specific supplier details including their tax identification numbers in the suggested address field while recording a purchase.
I hope this is implemented on priority.