party merge legal entity, customer and supplier

Summary:

During setup and migration three parties have been created for the same legal entity, supplier and customer. The merge of customer and legal entity went smooth, but the merge with the supplier goes into error.

Content (required):

During creation of the legal entity, a party is created with usage 'establishment'. For the same legal entity, also a supplier and customer has been created. These also have their own party with usage 'supplier' and 'buying' customer.

This creates issues if we want to add the tax registration to this customer and supplier. As the tax registration is already in use for the legal entity and related VAT setup.