Blueberry Muffins made with frozen blueberries

Hello, I have a load of frozen blueberries in the freezer which I need to use up and wonder how to adapt Delia's blueberry and pecan muffin cake to use them: do I defrost thoroughly first and then weigh, weigh and defrost, use as is but reducing liquid?

(Also have a packet of frozen depitted prunes - so I am going to do the same with them)

Many thanks for your help!