You could just do it real Carrillo. Although you could just let it go and add it by boiling your priming sugar in a bit more water and adding sterile boils water. You could even boil your sugar normal and a separate pot of h2O and boil that then add when cooled until topped off. You will just be raining the volume and diluting a little should be for though make sure you give it a gentle stir in bottling bucket or rack onto of the water already in there.
On Deck: Undecided
Primary: Cal Common 'Steam' Beer
Bottled: Ginger Porter, BirthdayIPA
Previous Brews: Everyday IPA