GHG Protocol – Scope 3.1 for Pass-Through Transactions

How should emissions be accounted for under the GHG Protocol when I purchase products on behalf of a customer (with the customer specifying the supplier and product), organize the logistics, and then resell the goods to the customer?

Do these emissions fall under Scope 3.1 (Purchased Goods and Services), even if I mainly act as an intermediary?

Does it make a difference whether
a) I charge no margin/commission (pure pass-through transaction), or
b) I receive a margin/commission?

What has been your experience with this in practice?

Which criteria (e.g., economic control, transfer of ownership, risk assumption) are decisive in this context?

Thank you for your insights!