'Free' downloads -- I need them to require manual activation

I just need to confirm that I have the proper process in place for this.

I sell products, both boxed and downloads, but one particular product is a free upgrade to existing customers. Since eligibility needs to be checked manually, I've activated the 'free charge' module, and set the order status to Pending.

This works great, but the only issue I can see is if someone includes this upgrade with another product, and selects a payment method which automatically activates the download -- such as Paypal. That way they'd basically get one product for free.

Anyone currently deal with a situation like this, and have a better solution than just hoping that this won't happen?