Let me help share some insights about setting up accounts for a company that does intermediation.
You can set up a service item to describe the types of service your company provides. Then, choose income for the account.
You can then create an invoice or sales receipt to record your transactions. You can refer to this related article for the usual A/R workflows in QuickBooks: Accounts Receivable workflows in QuickBooks.
This should help get you on the right track. Keep me posted if you have additional questions about setting up the service item. I'm here to help.