CISG Article 10
For the purposes of this Convention:
(a) if a party has more than one place of business, the place of business is that which has the closest relationship to the contract and its performance, having regard to the circumstances known to or contemplated by the parties at any time before or at the conclusion of the contract;
(b) if a party does not have a place of business, reference is to be made to his habitual residence.
Article 93 [Place of delivery]
1. Where the place of delivery cannot be otherwise determined, it is:
(a) in the case of a consumer sales contract or a contract for the supply of digital content which is a distance or off-premises contract, or in which the seller has undertaken to arrange carriage to the buyer, the consumer's place of residence at the time of the conclusion of the contract;
2. If the seller has more than one place of business, the place of business for the purposes of point (b) of paragraph 1 is that which has the closest relationship to the obligation to deliver.
Article 125 [Place of payment]
1. Where the place of payment cannot otherwise be determined it is the seller's place of business at the time of conclusion of the contract.
2. If the seller has more than one place of business, the place of payment is the place of business of the seller which has the closest relationship to the obligation to pay.