Updated Question:
Let's suppose:
Business A - Registers on the Portal and make some products/services available; Business B - Registers on the Portal and make some products/services available;
Business A clicks on the Business B product/service buy button;
Questions: By taking into consideration this should be a eCommerce transaction:
How will Business A pay ?
How will Business B receive the money of that transaction ?
What are the hypotheses here ? Are there too many ? If so, can you please superficially list some of them.