You can make the adjustment in "My eBay | Preferences | Payment from buyers | allow buyers to edit totals"
That is how I addressed the issue quite a while back and it worked. I will need to check Paypal as I don't recall off the top my head about Paypal. But I will look for you.
As far as the link... Is that the link in your AW2000 total amount due Invoices?
And do I understand you correctly, you want to be able to offer a total with insurance and a total without insurance??
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