Combine the berries, pineapple, sugar and butter in a pot. Heat over medium-low heat until sugar is completely dissolved, stirring constantly. Increase heat to medium-high and bring mix to a full rolling boil, still stirring constantly. Stir in liquid pectin. Return the mix to a full rolling boil, still stirring constantly. Boil, still stirring, for 1 full minute. Then remove pot from heat and skim off foam.

Cool the jam for 5 minutes, stir gently every minute or so to distribute the fruit. Then ladle into hot jars, leaving 1/4 inch headspace.

Process half pints in a 200 degree F boiling waterbath for 10 minutes and pint jars for 15 minutes.