I've got an edition of the one pot wonders cookbook with the syn values for EE in it as well. Just had a flick through and there are no recipes where the rule 'use the lowest syn value' doesn't apply.
My book has:
SOUPS: Caramalised onion soup to fragrant mussel broth
GREEN MAIN:Cheesy rice and aubergenie pepper melts to Wild mushroom and potato frittata
ORIGINAL MAIN: Beef, mushroom and carrot stew to savoury prawn and herb frittata
DESSERTS Creamy rice and rosewater pudding to baked vanilla cheesecase
If your book has the same recipes then the advice of simply going by the lowest syn value will be easiest to follow.