Sorry, I misread some of your first post. My comments still apply though.
I would actually focus on the couple who had just got married. They're paying so they better bloody well be in focus.
DOF covers roughly one third in front and two thirds behind based on distance to subject. Here's a link to a DOF calculator -
http://www.dofmaster.com/dofjs.html memorise or take notes and learn to judge distances if you can.
Applying some + or - ev adjustment depending on the situation would be a good idea.
From a metering point of view you would want exposure set for somewhere between the sky and the dark suit.
Shooting in RAW allows you to blow out the highlights some and rescue them in PP.
Looking at where the sun is and organising the subjects accordingly or getting yourself in the right position helps a lot.
I still recommend that book, you won't be disappointed.