Make sure your seltzer is fresh and full of fizz. There's a link for Regan's orange bitters which I used, as well as a few others I added to the online store.
1 ounce bourbon
1 ounce marschino juice (not liquer)
two generous splashes of vermouth
few dashes of orange bitters
Fill a cocktail shaker with ice. Pour in ingredients. Cover and shake until sweat beads form on outside. Strain into ice-filled rocks glasses. Add an equal amount of seltzer. Garnish each drink with a maraschino cherry.