PayPal - manual payment capture

We are in the process of launching a SuiteCommerce Advanced site, and I am trying to make sure I fully understand the PayPal with Express Checkout integration.

When an order is created from the site and the user chooses Paypal as the payment option, the payment shows up as pending on our Paypal account. We have the option to manually capture it. If I am understanding the NetSuite flow correctly, this will automatically capture once the sales order is fulfilled.

The hang up we are having is our payments in the past have been captured on the day the order is made, regardless of fulfillment status, and accounting prefers to keep it that way. We ran a few test orders through and then tried to do a batch capture of them, and this was not working. After contacting PayPal, they instructed us that a "DoCapture API request" must be initiated. I am assuming this is the request that comes from NetSuite automatically after the sales order is fulfilled. Admittedly, my knowledge of API communication is limited in this context.