Absolutely – make a single pledge, you're then offered the chance to 'Manage your pledge' (big blue button on the right of your screen). Then you'll need to change your total pledge amount to cover any additional items and resubmit your total. Then PLEASE send us a message to let us know which pledges you've gone for so we can adjust totals.
If you want to just change your pledge to a different reward, you have that option as well.
When the campaign's done we'll send out emails to double check what everyone wants.